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I am involved in a project related to speech analysis. I really need to record high quality speech sounds. I quickly realised computer sound card is not exactly what I need to use.

I do some research and realised that I'd just need some small but professional Audio Interface - I need one that works with MacBookPro Intel 64bit (iOS 10.6.x) - and Pro Condenser Mic. One of the requirements is fairly high sampling frequency, let's say 96+ kHz is ideal. From what I've seen there are couple of options: - Focusrite Scarlett, 2i2, No MIDI, 96kHz / 24bit, £119.99 - Lexicon Alpha, 2x2, No MIDI, 48kHz / 24bit, £48.50 - Alesis iO2 Express, 2x2, No MIDI, 48kHz / 24bit, £79.00 - M-Audio MTrack Plus, 2x2, MIDI In/Out, 48kHz / 24bit, £129.00 - Tascam iU2, 3x2, MIDI In/Out, 48kHz / 16bit, £84.99

Looking at numbers and smapling freq, I think Focuserite Scarlett 2i2 would be the best option. Would you recommend this Audio Interface.

Also, which mic would you suggest for high quality speech recording?

Thanks

EDIT: If you have any suggestion on different audio interfaces please feel free to prvide info :)

  • I would just expand on how you plan to use the recordings a bit, as this is very specific. Most mics add some 'character' to the sound, so are you interested in uncoloured, reference type recordings. Also, what are you trying to analyse? Are particular frequencies important for example? Why is a higher than 48khz sample rate important for you? I think you will get more useful answers this way. – Mark Durham Mar 10 '14 at 16:15
  • Hi Mark, I am interested in uncoloured / reference recording, as much as possible. OK. I don't know exactly which frequency range I should consider atm and that's why I want very high sampling frequency. I mentioned speech recognition but it will be speech/speaker recognition based on spoken words and phonemes plus perhaps different voice depending on physiological conditions. I cannot say much atm. – Celdor Mar 10 '14 at 21:40
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If you go for analysis you want to go as much steril and neutral as possible. So you need

  1. Very flat Microphone, Pre-Amp and A/D-Converter
  2. A very good treated room
  3. Very good isolated cables

To 1. I know that car companies use binaural recordings via DIN-Normed Microphones and Artificial heads. Look into something like "Harry" from Sennheiser. Moreover room measurement mics are said to have a very flat response. Also keep in mind that small condensers are better for measurement than large condenser, since they do have the typical "flappy" lowed of large condensers. Dynamic Mics are no option for analysis, since they have no good high frequency-respond. Then use the Mics with a carded pattern for mono or go for binaural recording or OSS or ORTF for stere, since those three stereo micing systems have a very natural, human alike sound. I would go for a A/D-Converter (Interface) with an inbuilt mic-preamp. The preamp should be transistor based and it should not color the sound. So channels from Presoues could be a great alternative.

To 2. You need either a completely flat room (you will need to hire an akustik pearson to build a very flat room) or a room that represents the typical situation of your experiment. If it is for example a test for a navigate system you want to use a car testing room where you can measure right in the car. The room is in most cases even more important as the mic and the other stuff, since it will colour your sound heavily by room resonances, took tone, reverb and early reflections.

To 3. Be sure to use good isolated cables and keep them away from any electromagnetic field (power adapters ect.)

I hope this goes yo a good starting point. Feel free to ask for more detailed infos.

  • Hi Tobias. Thanks for comprehensive answer. It gave me some thoughts. Audio interface Focuserite seems to have very good pre-amps. I may stick to it but I will consider the other option. The room is the problem. I may not have access to controlled environment; I will have to accept the conditions. However, I need to have clear recordings of a source rather than simulating specific environment. I was thinking if I can use any more "directional" microphone instead of cardio to overcome the room related problems. Cheers! – Celdor Mar 11 '14 at 11:20
  • Cardio is the most "directional" microphone in typical studio recordings, however there are boom/shotgun mics which hare used to record dialogue on film sets. They have a very strong directional characteristic. But the problem is not so the directional characteristic when it comes to recordings. Getting closer does not help that much with reducing the room tone in practice. Because most microphones are build for a recording distance of ca. 20cm to 1-2m. (Vocals speech typical 20-40 cm). You could contact a nearby sound studio and ask if you could do the test in their night shifts for... – Tobias Schmidt Mar 11 '14 at 12:56
  • ... a small fee or for free if its a scientific project. The not course you can credit them in your work. One thing so that can help you with getting better recordings are the portable recoding absorbers of rode microphones. Those combined with a great patch of acoustic foam above you can give good results. Moreover you can such devices for a small fee or build them yourself with rock wool coated in plastic and textile (Carfully rock wool hurts your eyes, skin and lungs so you need to wear protection). – Tobias Schmidt Mar 11 '14 at 12:57
  • Hello. This is really useful. Yes, it's a scientific project. I'll have a look at microphones and acoustic foams you've mentioned. Cheers! I could give your answer +1 but have not enough reputation. I cannot understand why I am restricted :p – Celdor Mar 11 '14 at 13:14
  • You need to have some reputation trough good questions and answers to get the right to vote, comment on other tracks etc. You can find the restrictions under your privileges tab in your stats. If you think my answer has solved your question you can accept the answer (the button below the voting button). Good Day! – Tobias Schmidt Mar 11 '14 at 19:35

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