Phonetics lab seminar 4/25/05

About microphones in general:

· “Learn more about microphone technology” http://www.dpamicrophones.com/page.php?PID=40

· excellent page: http://arts.ucsc.edu/ems/music/tech_background/TE-20/teces_20.html

· ANSI standards: Specifications for Laboratory Standard Microphones, Amer. Natl. Stand. Inst. S1.12-1967 (R1977), New York, NY

· from http://www.netyak.com/microphone.htm:

Condenser Refers to the properties of the microphone that convert sound to electricity. Condenser microphones are powered, often by a small voltage from the PC.

Dynamic Refers to the properties of the microphone that convert sound to electricity. Dynamic microphones utilize a magnet and are typically not powered.

Electrostatic Refers to the properties of the microphone that convert sound to electricity. Electrostatic microphones are powered, usually by a small battery.

Omnidirectional Refers to the direction from which the microphone will receive sound.  Omnidirectional microphones pick up sound from all directions.

Unidirectional Refers to the direction from which the microphone will receive sound.  Unidirectional microphones pick up sound from one direction.
Noise canceling Refers to the technology used in some microphones to eliminate background noise and feedback.
Echo canceling Refers to the technology used to eliminate feedback, or echo, between the microphone and speakers.

· Shure website on using microphones with computer soundcards has lots of background info, including the following picture: ( http://www.shure.com/support/technotes/app-soundcard.html)

Common audio connectors,

from left: XLR male, XLR female, 1/4" male, RCA male, Stereo 3.5 mm male

Things to remember:

· Dynamic microphones are sturdier than condenser, but generally are less sensitive.

· Condenser microphones need a power source, e.g. a pre-amp.

· A head-mounted microphone means that speaker head-movements won’t affect the recording. However, some closure voicing and nasalization will be missed.

· A unidirectional microphone (cardioid pattern) picks up less ambient noise than an omnidirectional microphone (as long as it is pointed at the speaker – that is, the TOP of the microphone should be pointed at the speaker’s mouth).

· A balanced XLR connection introduces less noise than other connections.

· A shorter connecting cable introduces less noise than a long one.

· A microphone with some kind of windscreen will be safer from bilabial plosive releases and other popping sounds that will overload the recording. Positioning the microphone off to the side of the mouth will also help with this.

About our microphones:

the tabletop microphone: Conneaut Audio Devices (CAD) Equitek IIB

electret condenser, variable polar pattern (controlled by switch) including cardioid (unidirectional); 10-18,000 Hz, 132 dB dynamic range; XLR connection

no link for this older model; CAD’s current Equitek series: http://www.cadmics.com/equitek_2.htm

the head-mounted microphones: Shure SM10A

cardioid, dynamic, close-talk, lowZ; 50-15,000 Hz; XLR

http://www.shure.com/pdf/userguides/guides_wiredmics/sm10a.pdf

(this and others below from http://www.shure.com/datasheets/guides-wiredmics.html)

(if you wanted a good head-mounted mic for direct computer input, buy the unbalanced version)

misc. microphones around the lab and in the cabinet:

Shure SP19L

cardioid, dynamic, lowZ, 80-13000 Hz; 1/4” phone

http://www.shure.com/pdf/discontinued/sp19.pdf

Shure SM48

cardioid, dynamic, lowZ, 55-14000 Hz; XLR

http://www.shure.com/pdf/userguides/guides_wiredmics/sm48.pdf

MidAmco 10MA110 (this is a mystery brand)

dynamic; 1/4” phone

Sennheiser MKH-415 directional condenser lowZ microphone (long and thin), XLR

Sennheiser MZA 15-UP battery adapter with XLR connection

(newer models at http://www.sennheiserusa.com/newsite/category.asp?transid=cat36)

(Marantz) Superscope EC-3S Cardioid Condenser Stop/Start (unusual connection)

Sony ECM-44B miniature wired lavalier (clip-on), omnidirectional, condenser, XLR

http://bssc.sel.sony.com/BroadcastandBusiness/DisplayModel?m=0&p=10&sp=81&id=40718

cheap computer microphones: e.g. Sennheiser m@m60

http://www.microphones.com/sennheiser/mm60.html

cardioid, 40-12500 Hz; 1/8” stereo connection

USB computer microphones: Telex M-540 (or older M-560) (currently hard to find new online)

microphone in the aero box: Panasonic microphone cartridges

http://www.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch (“microphone cartridge”)

[Bruel & Kjaer (B&K) microphones generally used for voice source analysis, but we don’t have any]

Our options for recording:

lab’s page on recording: http://www.linguistics.ucla.edu/faciliti/facilities/recording/recording.html

1) first to a tape, then into computer

· DAT deck at sound booth

o to get into computer: D/D sound card (instructions “from DAT” on Simon)

· analog cassette deck at sound booth

o to get into computer: A/D sound card (instructions on Simon)

2) direct to disk

· if possible, A/D is best done outside the computer, to avoid electronic noise

· 2 options for microphone to computer

o ordinary microphone into computer’s audio (e.g. Gretel with a Mac mic)

See http://www.shure.com/support/technotes/app-soundcard.html for detailed technical info.

The Shure A96F is a transformer with a female XLR on one end and an 1/8" connector on the other end, which boosts the microphone output for input to a sound card (or a camcorder) and thus allows XLR microphones to be used. http://www.shure.com/accessories/a96f.asp

For Macs: From http://www.shure.com/support/technotes/app-soundcard.html:

To interface a standard professional microphone with the Macintosh sound input port, a preamplifier must be used to boost the output level of the mic (typically less than 1 millivolt) to the level required by the sound card (about 100 millivolts). A standard 3.5 mm miniplug will fit into the sound input port in such a way that the bias voltage in the jack does not contact any of the conductors of the miniplug, and will not be fed to the microphone. A mono, unbalanced, auxiliary level signal that is carried by a one conductor shielded cable can be connected to the Macintosh sound input port by routing the audio to the tip of a mono miniplug and connecting the shield to the sleeve. The computer detects the presence of a mono miniplug and will set the input for mono operation.

o microphone with its own A/D (USB A/D microphones)

Caveat about using USB microphones is that on PCs, the input level can only be controlled through Windows's "Sounds and Audio Devices Properties", not through the recording program you're using, such as Audacity. (Note that the current version of Audacity does have on-screen input level monitoring, but you can’t use Audacity’s level adjuster.)

· 2 options for microphone to another device (external soundcards)

o microphone into USB Telex P-800 (no longer available?)

o microphone into USB Lexicon Pro Omega Studio (not yet available for use)

“Omega Studio is a completely integrated computer recording system that includes the Omega 8x4x2 USB I/O Mixer, Steinberg’s® Cubase LE audio and MIDI recording software, and Lexicon’s world-class Pantheon VST Reverb plug-in. An 8-input, 4-Bus, 2-output USB I/O mixer with inserts, instrument input, MIDI I/O and complete metering and monitoring functions gives you the freedom to record up to 4 tracks at once and mix without the need for additional mixing hardware. Two dbx Silver Series® mic preamps with 48V phantom power provide a pristine front end for high-end condenser or more common dynamic microphones, insuring premium sound quality from the first take to the last. TRS insert points allow you to plug in your favorite dynamic processors before the signal reaches one of the 4 busses, where 24-bit converters transform the analog signal into a digital masterpiece. The Omega I/O mixer also features channel peak indicators for each analog input as well as an assignable bargraph meter for the 4 busses. By monitoring the signal before the A/D converters, clipping and distortion can be averted, unlike software-only level monitoring that can miss “overs”, ruining the track.”

Detailed descriptions: http://www.acousticfingerstyle.com/LexiconOmega.htm,

http://www.musiciansfriend.com/srs7/g=rec/search/detail/base_pid/245505/

Info about several products: http://www.musiciansfriend.com/srs7/g=rec/search?c=9115

Bottom line/current recommendations:

¯ As of April 2005, we have no setup for direct-to-disk recording with a balanced (XLR) microphone. The signal can be sent to a pre-amp and from the pre-amp to the computer, but then the balanced property is lost. (Similarly with a device like the Shure A96F.)

· Therefore our best-quality option remains the 2-step process of recording to the DAT deck, and then D-to-D transfer to the computer.

· We do not know yet whether the Omega Studio, or some similar device, with a balanced microphone input, will offer a 1-step solution of equal or better quality.

¯ The Telex USB microphones (or equivalently, the Telex P-800) are usually better than a microphone into the computer soundcard, and are fine for most purposes, e.g. Ling. 103 recordings, illustrations for class presentations, analysis of intonation and even vowel formant frequencies, creation of stimuli for perception experiments where noise is not a concern. But be sure to monitor the input level so that the signal is not too weak.

¯ There is no longer any obvious use for the old dynamic microphones with the ¼” phone plugs. They were previously used to record into portable cassette recorders and the old spectrograph.