Surround and Digital Performer

19 DPP App_D 1/10/05 2:36 PM Page 41 }D Surround and Digital Performer Digital Performer contains many powerful tools and features for editing and mixing multi-channel (surround) formats. In addition to dedicated surround panning plug-ins, multi-channel bounce to disk, multi-channel editing, bass management, and calibration plug-ins are also provided. Incorporate these tools with DP s Movie window and the QuickScribe Editor, and you have a comprehensive environment for scoring and mixing sound to picture. The following section will discuss surround-mixing formats that are supported by Digital Performer and will also provide descriptions and explanations of the various encoding schemes (for example, Dolby Digital) that are available and relationship to specific surround mixing formats (for example, 5.1 format). Setup procedures such as monitor calibration and channel assignments are explained later in this appendix. The Surround Environment When working with surround projects, you should consider a number of factors. These include the following: Q Monitors. One of the most basic of considerations do you have enough speakers for the format you will be working in? And are your rear speakers full range? Q Monitor calibration. Proper speaker positioning and alignment are critical if you are planning to create surround mixes. Q Bass management. Consumer home-theatre systems usually employ some type of bass management. Proper bass management in the studio allows you to simulate this process, so that your mixes will translate and sound better in various listening environments. 41

19 DPP App_D 1/10/05 2:36 PM Page 42 APPENDIX D} Surround and Digital Performer Q Encoding. Multi-channel mixing formats (for example, 5.1) are different from surround encoding formats (data reduction schemes) such as Dolby Digital, DTS, and SDDS, which are used to compress, or reduce, the size of audio files so they can fit on the intended medium whether it is traditional film stock or DVDs. Of course, mixing formats and encoding formats are related; 5.1 files, for example, can be encoded to both Dolby Digital and/or DTS formats. Audio files must be properly encoded in order to play back on surround systems (of course, standard.aiff and.wav PCM files are supported). The encoding process is left up to the mastering or authoring stages of the post-production process. DP cannot do this encoding, so you will have to employ third-party software or dedicated hardware if you are doing the authoring yourself. Supported Multi-Channel Formats You can create surround projects that incorporate other surround formats besides the current industry standard, 5.1 format. Following is a list of supported mixing formats and their related encoding formats: Q QUAD. Front L/R and rear L/R channels. Q LCRS. Front L/R with center and mono rear channel (Dolby Surround ProLogic). Q 5.1. Front and rear L/R channels with center and.1 subwoofer (Film, Dolby Digital, and DTS). Q 6.1. Identical to 5.1, with center rear channel (Dolby-EX or THX Surround EX, and DTS-ES). This format is the extended version of 5.1 and is backward-compatible. Keep in mind that these three encoders are based on an encoding matrix, which basically mixes the extra rear channel with the L/R rear channels during the encoding process and is later decoded (for example, by the consumer home theatre) from those rear L/R channels. So technically, these formats are not true 6.1, as they are matrix-encoded. DTS-ES Discrete 6.1, however, is a truly discrete 6.1 format as it uses its own data stream and is not dependent on the rear L/R channels. This format is backward-compatible with DTS-ES. Regardless of which encoding format you employ, the end user s surround receiver (decoder) must support the extended format in order for the listener to hear the extra rear channel. Q 7.1. Identical to 5.1, but with additional L/R center channels (SDDS). Q 10.2. This format really consists of 14 channels: three front channels (L/C/R), two elevated front L/R channels, two side L/R channels, three rear channels (RL/RC/RR), elevated RL/RR channels, and two subwoofers. Though misleading, this format maintains the name 10.2 to demonstrate its relationship with 5.1. 42

19 DPP App_D 1/10/05 2:36 PM Page 43 Q The Surround Environment Encoding Encoding is really the last stage of the surround music production process. Encoding is typically performed in either the mastering or DVD-authoring stage. If you are an engineer who must send files off to be encoded, proper preparation is critical to ensure that the front left channel doesn t get accidentally placed in the center, and so on. Channel assignments vary according to the encoding format that will be used. Regardless of the format, however, proper naming of each audio file (for example, front-left, front-right, center, rear center, and so on) can help ensure that the tracks are placed in their proper channels. Encoders or data reduction schemes are used for basically two reasons: to provide discrete channels of audio for playback and to reduce the amount of bandwidth (measured in bps, or bits per second) and space that the audio consumes on the intended medium (for example, film and DVD). Make sure you don t confuse data compression with dynamic compression, which is a totally different beast. There are various competing encoding formats on the market, each having its strengths and weaknesses. A few of the major formats are discussed below. Dolby Digital and Pro Logic Dolby Digital, also known as AC-3 encoding, is the de-facto standard of the movie industry, and is flexible in that it supports up to 5.1 channels, meaning that not all Dolby Digital soundtracks contain six channels. The Dolby 1.0 format consists of one mono channel, Dolby Digital 2.0 consists of two channels, Dolby Digital 4.0 consists of four channels, and Dolby Digital 5.0 contains five channels of audio (5.1 minus the.1 subwoofer). The 5.1 format consists of five discrete channels of fullspectrum audio (L/R/C/RL/RR with a frequency range of 20Hz 20kHz) with a.1 LFE channel (subwoofer). The sub is designated as.1 because its frequency range is not full range, and is usually between 30Hz 120Hz. When film is the final medium, the AC-3 encoded file is embedded between the sprocket holes of the film as 78 78 black and white pixels. As the space is limited, Dolby Digital employs a sophisticated perceptual encoding system to data-compress the audio data while preserving the integrity of the audio. If you are authoring to DVD, you can control the amount of data reduction (up to 448bps), depending on the available space. For example, if you have the space, you can employ higher bit rates, resulting in less data compression and higher fidelity. Choosing AC-3 as your encoding format can help ensure playback capability on older consumer home-theatre systems. 43

19 DPP App_D 1/10/05 2:36 PM Page 44 APPENDIX D} Surround and Digital Performer Q A.PACK (AC-3 ENCODING SOFTWARE) Apple s DVD Studio Pro (DVD authoring software) comes bundled with an application called A.Pack (see Figure D.1). This program encodes audio files (.AIFF, SDII,.WAV, and QuickTime soundtracks) into the AC-3 format (mono-5.1). This encoder also includes features such as batch processing, stereo down-mixing to check the encoded files, and the ability to decode AC-3 files to PCM files. Figure D.1 The A.Pack AC-3 encoder application comes bundled with Apple s DVD Studio Pro DVD authoring software. DTS The Digital Theatre Systems (DTS) format also supports 5.1 (even true 6.1) surround, but supports higher bit rates than Dolby Digital (up to 1536bps), which results in all those DTS sounds better than Dolby Digital statements and testimonials. As DTS encodes at higher bit rates, it takes up more space than AC-3 audio. To get around this limitation when working with film, DTS audio is actually supplied as separate CD-ROMs that are synced to the film via an optical timecode track. This timecode track is recorded directly on the film, between the analog soundtrack and the actual picture frame. If there is a timecode drop (which is extremely rare), the DTS system seamlessly switches to the film s analog audio track to prevent any playback interruptions. DTS is one of the few encoding formats that is not based on the DVD spec. 44

19 DPP App_D 1/10/05 2:36 PM Page 45 Q The Surround Environment When working in the DVD format, DTS audio is supplied as an optional playback format (in addition to AC-3), as it is not the standard encoding format. DTS has just received a further boost within the MAC DVD authoring environment, however, with the added support for the DTS format in Apple s DVD Studio Pro 3 software. Q DTS: PRO AUDIO ENCODERS As of this writing, DTS has introduced a new line of pro software audio encoders for the Mac and PC for creating DTS soundtracks for DVD-Audio, DVD-Video, and 5.1 CD titles. The stand-alone DVD-A and DVD-V encoding solutions are capable of delivering either 48kHz/5.1 soundtracks or 96kHz/6.1 extended surround DTS tracks, depending on the package you choose. Both stand-alone applications will accept.wav and.aiff files for encoding. The 48kHz solution also provides the capability to encode 44.1kHz CDs. On the Apple Xserve RAID front: The new TS X Encoder allows up to 99 multiple users (on either Mac or PC platforms) to encode DTS surround soundtracks via an intranet, allowing users to encode files remotely! You can get more information on these new encoders at http://www.dts.com. SDDS Sony Dynamic Digital Sound uses a format called ATRAC to reduce the data rate of the multi-channel audio and is recorded as blue and white pixels outside the sprocket holes. To ensure reliability, both sides of the film are recorded to; this adds a layer of redundancy. MPEG 2 MPEG 2 (MPEG 1 Layer 2) is based on the MPEG 1 format, and the files are similar to MP3s, which are MPEG 1 Layer 3 files. Within the MPEG format, only Layer 2 files are allowed in DVD-video. MPEG 2 supports up to eight channels of audio and is similar to the AC-3 format. MPEG 2 audio is not compatible with all NTSC DVD players, so you should employ other encoding schemes if you want to ensure full DVD player compatibility. Q APPLE S COMPRESSOR Another encoder that comes bundled with Apple s DVD Studio Pro application is Compressor. This program is designed to data-compress audio and video to a wide range of formats, including MPEG-2. Support for automated batch processing, variable bit rate (VBR) encoding, format presets, and high quality filters (noise-reduction, color correction, and gamma adjustments) is included. 45

19 DPP App_D 1/10/05 2:36 PM Page 46 APPENDIX D} Surround and Digital Performer Surround Setup Compared to traditional two-channel mixing, multi-channel surround recording, editing, and mixing is a fairly complex process. Speaker positioning, monitor calibration, references levels, and bass management are some of the details that need attending to. In this section, I ll discuss the basic procedures for getting the most out of your DP surround setup; I ll also offer DP related tips and shortcuts. Surround mixing is a complex process, however, and covering every scenario and process is beyond the scope if this book. See Appendix E, Additional Resources, for a list of related Web sites or books that may help you to further expand your surround knowledge. Monitor Setup It goes without saying that you need to make sure you have the number of speakers for the surroundmixing format in which you wish to work. Each speaker will need to be connected to an output channel of your audio hardware interface six channels for 5.1, eight channels for 7.1, and 14 channels for 10.2. 5.1 Speaker Placement When you re working in 5.1, you must adhere to specific speaker placements as defined by the International Telecommunications Union, or ITU. The front three speakers should be arranged left, center, and right. The angle between the left (L) and center (C) speakers and between the right (R) and center (C) speakers should be 30. Each speaker should be placed at an equal distance from the listener, so the center speaker should be placed slightly further back (in an arc) in relation to the left and right monitors. If you can t position the center channel properly because of the way your studio is set up, you should delay the center channel to compensate. The left rear (Ls) and right rear (Rs) surround speakers should be placed at an equal distance from the listener as the front speakers and should be angled at 110. For example, if the front speakers are three feet from the listening position, the rear speakers should also be at a three-foot distance. Standard Reference Levels Reference levels vary depending on the intended playback medium (for example, film or TV) and the specific speakers within the surround setup. Front and Rear Speakers The standard is to set the level from each speaker one at a time so that pink noise generated at 20dBFS (the SMPTE standard) on a digital system (for example, Digital Performer) reproduces sound at 85db SPL. As you may have guessed, you will need an SPL meter or a Real Time Analyzer (RTA) for this. If you are using an RTA, each speaker should read 70dB SPL, which, when both left and right channels are combined, will produce an 85dB reference level. 46

19 DPP App_D 1/10/05 2:36 PM Page 47 Q Surround Setup There are two main reasons why audio levels are referenced to a certain amount: one is to provide consistency between reels within a movie theatre, and the second is so that you have enough headroom for those loud explosions, rumbles, and so on. When setting levels for the rear channels, however, there are two different approaches, depending on what you are mixing. With standard music and television, all five channels are set to the same level, while film and cinema applications require the rear speakers to be set at 3db lower, or at 82 db SPL. This concept is a by-product of the Dolby Surround days, in which the left and right rear speakers reproduced the rear-mono channel. Setting them 3db lower would reproduce a level that would be equal to one front channel. When working strictly with music applications, these levels tend to get thrown out the window, which is a shame, as it results in the whose CD is louder wars! Subwoofer The subwoofer also requires specific care and feeding. The LFE channel is designed to have +10dB of headroom and also replays 10dB louder than the other speakers. Broadband SPL meters are not ideal for this measurement as the subwoofer s frequencies are restricted (30Hz 120Hz). You should use an RTA meter that allows you to analyze just the lower frequency bands (for example, a third octave analyzer). If you don t have access to an RTA meter, however, you can work around it, though your results will be a little more approximated. There are a few different approaches to setting the reference level for the LFE channel. Q 10dB Setting. Set the pink noise level to 30dBFS for a measured reference level of 70db SPL on an RTA meter (approximately 79dB SPL with an SPL meter). Q +10dB Setting. Keep the pink noise level the same as for the front speakers ( 20dBFS) so that your RTA meter reads 80dB SPL (approximate SPL meter reading should be 89db SPL). Q +4dB SPL. If you do not have an RTA meter, set the pink noise to 20dBFS and filter it so that it only has frequencies between 20 and 120Hz. Set the reference level so that the SPL meter (set to a C weighting) reads +4dB higher than the main speakers, or approximately 89dB SPL. Q Bass Management. If you are using bass management (which you should be!) then you also need to calibrate DP s Bass Management plug-in by adjusting the Extend Trim knob. Audio Bundles The first thing you will need to do when setting up your DP system for surround is to create a multichannel bundle for the format you wish to work in (for example, 5.1 bundle) within the Audio Bundles window (see the Audio Configuration section of Chapter 2). Once you ve created it, assign the outputs of your tracks to this new surround bundle and begin working. The drawback to this sim- 47

19 DPP App_D 1/10/05 2:36 PM Page 48 APPENDIX D} Surround and Digital Performer ple setup is that no matter what you are mixing (for example, center channel dialog, stereo music bed, and so on) you will always have to use a surround panner to place audio within a speaker. As surround panners consume CPU resources, this isn t a very efficient setup. There is a way around this extra CPU consumption. DD-consumption DP allows you to create bundles that share the same outputs as other bundles. So you could, for example, create a separate mono bundle for the center channel. This would let you place dialog in the center without using a CPUhungry surround panner. Exactly how many bundle types you create is really up to you just be sure to rename them something that s easily recognizable. In case you re having a problem imagining the different bundles that you might need, here are a few examples to get you started in a 5.1 scenario (see Figure D.2): Q 5.1 Bundle. Start out by creating this bundle. You ll need this for your Master Fader and any other sounds that you may need to place in all speakers (for example, FX, special music cues, and so on). Q Center. Create a mono bundle for the dialog track. Q Stereo. Create a normal stereo bundle for the front left (L) and right (R) speakers. This is typically used for the music bed. You can, of course, also place the music in the rear channels it really depends on your mixing needs. Q QUAD. You could create a QUAD bundle consisting of front left/right and rear left/right speakers for the music bed reverb or any other elements that do not require the center and LFE channels. Figure D.2 DP allows bundles to share the same hardware outputs as other bundles. 48

19 DPP App_D 1/10/05 2:36 PM Page 49 Q Surround Setup Q CHANNEL ASSIGNMENTS BY FORMAT Channel assignments are the order in which each channel should appear within your master surround recording. Should the front left channel be assigned to output 1 or output 3? What order should you configure your 5.1 Audio Bundles to be? Believe it or not, there is a method to the madness, and it strictly depends on the intended surround format. Below is a list of various formats and their channel assignments: Film track standard. Left Front/Center/Right Front/Left Surround/Right Surround/LFE Dolby, SMPTE, and ITU standard. Left Front/Right Front/Center/LFE/Left Surround/Right Surround DTS. Left Front/Right Front/Left Surround/Right Surround/Center/LFE SDDS. Left Front/Left Center/Center/Right Center/Right Front/ Left Surround/Right Surround/LFE The Dolby configuration is the channel assignment standard. The film track standard is seen in film studios and also in some music production situations. The DTS and the SDDS formats must be used when encoding in their proprietary formats. If you are in doubt, use the Dolby standard and be sure to label each audio file by its channel name. Basic Panning Puck Once a multichannel bundle has been created and your track s outputs are assigned to a multichannel bundle, the standard stereo panning will be replaced with the surround-panning dish (see Figure D.3). The little ball in the Mixing Board s circular surround matrix is called the puck; it allows you to pan within the surround field. Simply drag the puck to pan. The green indicator ring displays the panning Figure D.3 The surround-panning dish. Move the panner puck into a pocket to pan directly to different speakers direction of the signal, or which speakers the signal will be occupying. The individual channels (speakers) are represented by the half circles, or pockets. If you would like to pan discretely to a specific speaker, push the puck into one of the speaker pockets. To mute a channel, click on a speaker pocket with the mouse; it will turn orange, indicating the muted state. You may have noticed that there is no pocket for the LFE channel you will need to open a panner plug-in for LFE control. 49

19 DPP App_D 1/10/05 2:36 PM Page 50 APPENDIX D} Surround and Digital Performer Q JOYSTICK CONTROL Digital Performer also has support for USB joystick controllers. Simply choose Enable Joystick Controller from the Mixing Board s mini-menu to enable the joystick. Next choose Configure Surround Panner Joystick to launch the Joystick Setup window. Set the mixing function on the left side of the window to the joystick movement on the right side of the window (see page 671 of the Digital Performer manual). Surround Panner Plug-ins To give you greater control, Digital Performer employs a panner plug-in architecture that allows you to choose exactly which type of panning dish to work with on a channel. Besides LFE panning capabilities, dedicated surround panners also contain options and features for greater control over the surround field. To access the Panner Plug-in menu (see Figure D.4), click on the Panner Window Open button located to the right of the panning dish (this is the down-arrow icon). You can also click on the default Panner Window Open button (the circle icon located to the right of the panning dish) to open the default panner plug-in. To set the default panner plug-in, choose Mixing Board > mini-menu > Set Default Surround Panners. The Default Surround Panners window will open, allowing you to choose the default panner (see Figure D.5). Figure D.4 The Panner Plug-in menu provides a drop-down list of the four panner plug-ins. Figure D.5 Set the default panner plug-in from the Default Surround Panners window. Many of the features in each panner are similar, so we ll highlight some panner basics within the Tri- Pan plug-in. 50

19 DPP App_D 1/10/05 2:36 PM Page 51 Q Surround Panner Plug-ins Tri-Pan Plug-in The Tri-Pan plug-in (see Figure D.6) provides two basic surround-panning positions: left to right and front to rear. You can pan freely within the Pan Grid simply by grabbing the panning puck with the mouse (2-Knob mode). If you want to have your panning movements constrained to a straight line, use 3-Knob mode. In addition to the standard position and filter controls, the Tri-Pan plug-in also lets you control divergence (explained later). Joystick Mode When mono-to-surround or stereo-tosurround plug-in versions are launched, they will first open in Joystick mode. Joystick mode provides a panning grid that allows you to pan signals by dragging a red puck (which represents the audio signal) freely within the Pan Grid. You can also click on a speaker icon to pan directly within a specific channel. Joystick mode can be chosen by clicking on the Joystick button (see Figure D.7) represented with a square button with a red dot in the middle located directly above the Pan Grid s left speaker icon. The button located to the right is the Faders button (explained later). Figure D.6 The Tri-Pan plug-in. Figure D.7 The Joystick Mode (left) and Faders Mode buttons (right). Position The Position section provides another way for setting the front (L/R), front/rear (f/r) positions, and rear panning positions. You can use the +/- buttons to type directly into the field controls. The 2-knob setting links the front and rear panning knobs together, but doesn t constrain diagonal panning movements. When 3-knob is engaged, you will see a white line appear with three pucks (dots). The middle puck indicates the position of the audio signal. The outer pucks represent the y-axis, constraining any panning movements to these front and rear pucks. This allows you to pan in a straight line without any unnecessary moves. To change the destination of the signal, simply drag the outer pucks to the desired positions. 51

19 DPP App_D 1/10/05 2:36 PM Page 52 APPENDIX D} Surround and Digital Performer Divergence Divergence controls the width of any panning. Values of None will let you pan normally and place signals exclusively within a designated speaker. Choosing higher values will force a signal to bleed into adjacent speakers, regardless of its panning position. Setting each control to Full, for example, would cause the signal to remain in the center, even if it was panned left or right. Divergence allows the mixer to adjust the width of panning depending on the size of the intended listening environment. Within the Pan Grid, Divergence is represented with white dots connected with blue lines. Drag a dot to change the Divergence setting. Filters Filters are provided for signals that can be assigned to an LFE channel. The Pre-LFE setting lets you roll off frequencies (typically, anything above 120Hz) before they get to the subwoofer. If you want to filter the LFE channel at the output stage, set this feature to 20Hz. The Pre-Pan setting allows you to filter frequencies lower than 120Hz for instances in which you are using an LFE channel. Meters, Solos, and Mutes Click the disclosure triangle (located above the front-right speaker icon) to access the hidden Meters, Solos, and Mute buttons (see Figure D.8). Figure D.8 The Meter pane can be accessed by clicking on the disclosure triangle icon. Disclosure triangle 52

19 DPP App_D 1/10/05 2:36 PM Page 53 Q Surround Panner Plug-ins Faders Mode Click on the Faders mode button to change from the Pan Grid to Faders view. Faders mode provides an alternative method for surround panning. Instead of maneuvering the surround puck within the Pan Grid, you use faders to decide how much of a signal is sent to a certain speaker. Fader sends are calibrated to control signals in 1/10dB increments. Mono-to-surround panners will contain one fader for each surround channel (see Figure D.9), while stereo-to-surround panners will have two faders for each channel (see Figure D.10). Surround-to-surround plug-ins, however, will only operate in Faders mode. Figure D.9 Mono-to-surround panners contain one fader send for each surround channel. Figure D.10 Stereo-to-surround panners contain two fader sends for each surround channel. 53

19 DPP App_D 1/10/05 2:36 PM Page 54 APPENDIX D} Surround and Digital Performer N-Panner The N-Panner plug-in (see Figure D.11) is a simpler version of the Tri-Pan plug-in, minus the dedicated Divergence controls and 3-Knob mode. The Focus control is a simplified divergence control that diffuses a signal across the front channels. Figure D.11 The N-Panner is DP s most basic panning plug-in. Arc Panner The Arc Panner plug-in (see Figure D.12) contains a radial grid for detailed panning. As with the basic Surround Panning dish, a green indicator ring provides additional visual feedback on the panning position. Figure D.12 The Arc-Panner plugin provides a radial grid for panning. 54

19 DPP App_D 1/10/05 2:36 PM Page 55 Q Surround Panner Plug-ins Auralizer The Auralizer Panner is a cross between a Surround Panner and spatial-fx plug-in (see Figure D.13). This plug-in provides a unique approach to the positioning of a signal within the surround field. Instead of using gain to send a signal to a speaker(s), you use the surround puck to position the sound within a three-dimensional space. The puck s distance from the center is used to determine the distance of the signal from the listening position. Figure D.13 The Auralizer plug-in is more of a spatial-fx plug-in. This plug-in is great when you re working with sound effects or Foley tracks within a film or video score. Clever features like Doppler and Head values (explained later) let you easily simulate natural acoustic phenomena, providing the listener with a more realistic viewing experience. Position Angle and Distance values are used to determine the position of a signal in relationship to the listening position. The Width value is measured in meters, and it controls the width of the signal. Higher values, when used in combination with the Distance setting, allow you to give the listener the perception that signals grow wider as they approach. 55

19 DPP App_D 1/10/05 2:36 PM Page 56 APPENDIX D} Surround and Digital Performer Room The Room settings control the acoustic properties of the room the signal is occupying or traveling in. Size determines the average distance between walls in the virtual room, while Absorption controls the reflective properties of these walls. Volume is expressed in cubic meters and sets the total volume of the room. Use the Emphasis setting to change the effects of the Position values. This may be helpful if you are using this plug-in for signals that require a more traditional panning approach, such as a music bed. Psycho-Acoustic Cues These settings are used to simulate the way the brain gathers different acoustic events to determine a sound s position relative to the listener. You can use these parameters to more control how sound travels within an acoustic space. Q Doppler. Doppler shifts are inherent in the laws of physics. Sound that is approaching an object will sound higher in pitch, while sound traveling away from a listener will sound lower in pitch. The Doppler option allows you to simulate this acoustic phenomenon. The rate at which the sound approaches and travels away from the listening position determines the rate of change. You can use the Emphasis option to affect this change. Q SIMULATING DOPPLER SHIFTS If you are trying to simulate a realistic Doppler shift, keep in mind that sound travels approximately 1150 feet per second. Translated into musical pitches: A sound source approaching you at 75mph will sound 10 percent higher in pitch, or approximately a musical one-half step higher, while sound traveling away will sound one-half step lower. Q Head. This parameter simulates the delay and frequency masking that occurs when a sound source is located to the left or right side of your head. Use the Delay setting to reproduce the inherent delay that occurs when a signal is positioned to the left or right side of your head. Use Shadow to mimic the high-frequency dampening that happens when a sound is located at one side of your head. For example, if you position a sound to the right side of your head, the left side will contain less-high frequencies. Q Distance. Simulates the effects that distance has on a sound source. The further the distance, the quieter the sound source will be. Reflections controls the volume of early room reflections. Reverb will diffuse the room reverb more as the sound moves away from the listening position. Attenuation controls the volume of the actual sound source. Sounds that are further away will become quieter. 56