Sound Cards
for use with Virtuoso™ Instructional Control Software
and Soloist® Digital PC Comparative Recorder
“Sound cards are like snowflakes – no two are alike.”
The Sony Virtuoso Series all-digital, PC-based language learning systems utilize the sound card in Windows®-based PCs for audio functions including playback and recording of sound files and audio “streams”. As such, the audio quality of the system is largely dependant on the quality of sound cards used. In addition, the system can take advantage of a number of more advanced capabilities incorporated in some sound cards – capabilities that are not often printed “on the box” or even listed in the sound card’s specifications. Some customers desire all of these capabilities (which are described below), while others do not.
We are often asked for a list of “compatible” sound cards. While it is one thing to state that the sound card should be “Intel® AC ‘97” compliant, or “Sound Blaster® Compatible” (which it should be), the capabilities listed below are not necessarily required to make them compliant as such. It is not possible to test every combination of sound cards (all makes, models and revisions), Window versions, and driver files for capabilities that not all customers require. In many cases, the same identical sound card will behave quite differently under different versions of Windows/Service Packs and/or with different driver files/versions (which could be supplied by Microsoft®, the PC manufacturer, or the sound card manufacturer).
Moreover, most desktop and laptop PCs include a “sound card” on the motherboard. While there are a limited number of chipsets used by PC manufacturers, it is usually the PC manufacturer that supplies the driver files (and updates) – the same chipset on different PCs has been observed to have very different capabilities. It is not uncommon for major PC manufacturers to issue driver updates to resolve problems. Imagine a student taking the oral portion of the AP® examination believing they are recording only to find that the recording plays back faster than expected (affecting pitch) or is not nearly as long as they thought, cutting off their recording. These are two real examples of problems found with driver files supplied with PCs from a “reputable” manufacturer (refer to SANS Knowledge Base Articles 30807-A and 30807-B for details). Other problems observed with faulty driver files include hearing an “echo” type sound when playing back a comparative recording.
Customers with desktop PCs may determine the on-board sound card has all the capabilities they desire, and if not, they can choose to install another sound card in the PC. That is not currently a practical choice for laptop users.
Sound Card Capabilities Used by Virtuoso/Soloist Software
• Full-Duplex
The sound card should have “full-duplex” capability – meaning it is able to record and playback simultaneously. This is a fundamental necessity for Soloist to be able to perform “comparative recording”, playing one track of a sound file (the lesson material), while simultaneously being able to record the student’s voice to the other track of the same file.
Full-duplex capability is found in nearly all sound cards and is part of the AC ’97 specification. A simple way to determine if a sound card is full-duplex capable is to play any audio file with Windows Media Player and attempt to use Windows Sound Recorder to record (from any source). If the sound card is not full-duplex capable, Sound Recorder will indicate that recording is not possible because the device (sound card) is being used by another application (Media Player).
• Multiple Simultaneous File Playback
The sound card should be capable of playing multiple sound files (or “streams”) simultaneously.
This is necessary if it is desired to be able to playback (hear) the sound in a video file that Soloist may be playing, while at the same time playing back (hearing) any voice recording the student may have performed. In addition, with the optional VirtuosoP3 “Multicast Video” plug-in module, this capability is needed for Soloist to be able to playback the audio from a multicast video source while simultaneously playing back any student recording.
This capability is found in most sound cards. A simple way to determine if a sound card is can play multiple sound files simultaneously is to play any audio file with Windows Media Player and attempt to play another sound file with another instance of Media Player at the same time.
• Microphone Playback Control
(In legacy hardware-based language labs, this is sometimes referred to as “E-to-E”, “Audio Active” or “Side Tone”.) The sound card should be capable of adjusting the volume of the microphone input on the “playback side” of the sound card’s mixer. This is necessary if the students are to be able to hear their own voice as they speak.
While most sound cards are capable of this, it has been observed not to be the case with some sound cards, particularly on some laptop PCs (most probably intended to prevent feedback from using a built-in microphone and speakers).
To determine if a sound card has this capability, plug a headset into the proper sound card connectors and, using either the Windows “Volume Control” or mixer software provided with the sound card, attempt to adjust the Microphone “playback” volume and listen to determine if you can hear yourself speaking.
Sample Sound Card Mixer “Playback Side” Controls (Using Windows ‘Volume Control’)
• Record “Mix” Capability
The sound card should be capable of mixing multiple audio sources on the “record” side of its “mixer” (this capability is not used with Soloist running in a “stand-alone” configuration). This is necessary for features such as the teacher being able to hear a student speaking as well as any file they may be listening to.
While all sound cards include what is referred to as “mixers” (one for playback and one for recording), most do not have true mixers on the “record” side; rather they are “selectors”. Mixers are capable of mixing (or blending) multiple sources at the same time while selectors can only select one source at a time. Some such sound cards have a single “Mix Buss” as one of the selections – sometimes called “Wave Out Mix”, “Stereo Mix”, “Mono Mix” or “What U Hear”. Although this is part of the AC ’97 specification, it is not found in all sound cards.
Sample Sound Card Mixer “Record Side” Control (Using Windows ‘Volume Control’)
• Multiple Supported Sample Rates
The sound card should be capable of mixing multiple audio sources on the “record” side of its “mixer” (this capability is not used with Soloist running in a “stand-alone” configuration). This is necessary for features such as the teacher being able to hear a student speaking as well as any file they may be listening to.
While all sound cards include what is referred to as “mixers” (one for playback and one for recording), most do not have true mixers on the “record” side; rather they are “selectors”. Mixers are capable of mixing (or blending) multiple sources at the same time while selectors can only select one source at a time. Some such sound cards have a single “Mix Buss” as one of the selections – sometimes called “Wave Out Mix”, “Stereo Mix”, “Mono Mix” or “What U Hear”. Although this is part of the AC ’97 specification, it is not found in all sound cards.
The term “sample rate” is indicative of the sound quality as it relates to frequency response (refer to the SANS White Paper entitled “Digital Audio Primer”). “CD-quality digital audio” uses a sample rate of 44,100 Hertz. For language learning use, where it is necessary to accurately reproduce the human voice, a sampling rate of 22,050Hz is more than sufficient. Nearly every sound card supports the 22,050Hz sampling rate.
There are two distinct cases where the sample rate applies with the Virtuoso/Soloist system. First is to record and play digital audio files – the higher the sampling rate, the larger the files (refer to SANS white Paper “Audio File Compression”). Virtuoso and Soloist support all sampling rates the sound card supports. The other case is transmitting (streaming) audio over the PC network – the higher the sampling rate, the more bandwidth required. In addition to 22,050Hz, Virtuoso and Soloist support sampling rates of 16,000Hz and 8,000Hz for this. If it is desired to reduce network bandwidth requirements, the sound card should support one of both of these sampling rates. While all these sampling rates are part of the AC ’97 specification, not all sound cards support them all.
• Line Input Connector
It may be desirable to connect a tape recorder to the either the student or teacher stations (for example to digitize analog audio cassettes or to use tapes as a source to be streamed to students).
In such case, the sound card would need to have a “Line Input” connector (an AC ’97 specification requirement). While common on most desktop PC sound cards, it is rare on laptops PCs.
• Internal Connection to the CD-ROM Drive
At the teacher station, the Virtuoso software is able to control a CD-ROM drive for playback and “streaming” CD-Audio discs. In order to hear the CD audio, the drive must have an audio “connection” to the sound card (again, an AC ’97 specification requirement). In some cases, this connection is an internal cable between the CD-ROM drive’s analog audio output and the sound card’s “CD” input. Alternatively, some sound cards can capture the digital audio data directly from the CD.
• Headset Compatibility
The headset is another major determining factor of system sound quality. Most “off-the-shelf” headsets available from PC suppliers do not have headphones that are circum-aural” (covering the entire ear) and use low-quality, non-directional dynamic microphones. Such headsets prove to be far inferior to headsets with circum-aural headphones to block out ambient sound and a high-quality, directional electret-condenser microphone to minimize electrical noise (because of better dynamic range) and the pick-up of ambient sound (because of the directional characteristics).
However, unlike dynamic microphones, electret-condenser microphones require power (called a “bias voltage”) to operate. The ability of a sound card to supply a bias voltage via its microphone input connector for electret-condenser microphones is not a part of any international standard or compliancy specification. Most sound cards do supply a bias voltage, some don’t – you probably will not find this capability listed in the sound card’s specifications.
To further complicate matters, there are two different methods used by sound card manufacturers to supply a bias voltage; by using either a two-conductor microphone input connector with the bias voltage supplied on the “tip”, or by using a three-conductor connector with the bias voltage supplied on the “ring”.
If you are unable to determine if and how a sound card supplies a bias voltage, the only way to determine if an electret-condenser microphone will work with the sound card is to plug it in and try it. Listen to hear yourself speaking (if the sound card has a Microphone Playback Control as described above) and/or record your voice (with the sound card’s mixer “record side” input set to “Microphone” volume adjusted appropriately) then play it back.
• Microphone Boost Capability
Some sound cards provide an “Advanced” “Boost” control for the microphone. This control (sometimes refer referred to as “20dB Boost”) can provide additional gain for the microphone signal, which may be desirable depending on the headset used and the acoustical characteristics of the environment.
Sample Sound Card “Advanced Controls for Microphone”
(Using Windows ‘Volume Control’)
• MIDI Synthesizer
Most sound cards include an on-board music synthesizer that is compatible with the Musical Instrument Digital Interface (MIDI) standard. The synthesizer is capable of playing music based on data contained in MIDI files. Soloist is capable of controlling the sound card synthesizer to playback MIDI music files while allowing the students to record their voices. If there is no on-board synthesizer, there will be no MIDI file playback. Also note that the quality of the on-board synthesizers varies widely.
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