Back in Podcast 193 community member Michael Khaleel asked a question about audio above 20kHz after he watched a video of Rupert Neve giving a lecture at CRAS in 2001 in which he referenced the 'inaudible' frequency range well above 20kHz, as significant to a pleasant listening experience. Then in Podcast 195, community member Al Future responded with some of his thoughts on the subject.
Michael Khaleel asked to to discuss three questions...
- Is it more a function of sample rate and microphone range, than converter, that allows us to capture this desirable frequency range?
- If 192kHz 'replays' 96kHz in stereo, then are speakers that can reproduce that range also necessary to 'hear' the audio properly?
- Are such speakers presently available and are they within reach cost wise, of the home studio market?
You can listen to what we said on Podcast 193 at around 52'03"..
Then in Podcast 195 we read out a response to this from Al Future which we thought deserved a wider airing too...
Greetings from sunny Tasmania! Firstly, thanks for the podcast, tutorials, reviews and everything you all do. I've lurked for a long time enjoying the conversations and info. Now it's time to join in! I wanted to mention something in relation to the question from Michael Khaleel about audio above 20kHz. I think it's worth noting that most analogue equipment doesn't exhibit (or have designed in) a sharp roll off in the top end in the same way that an A/D converter does.The anti-aliasing filters on the inputs to A/D converters and outputs from D/A converters are very, very steep, set at (of course) just below half the Nyquist frequency (i.e. half the sample rate).
Fully analogue microphones, speakers, preamps and other purely analogue equipment generally do not intentionally roll off this steeply. Most specs quoted for speakers and microphones are indicating the frequency band within which the response lies within a certain range above or below a mean value. For example this might be indicating the -3db, -6dB or -10dB points at each end. So, a speaker quoting a frequency range of say 43Hz to 30kHz still has a response outside of these ranges, just not output that fits within the quoted range. It's similar for microphones and other equipment.
Thanks to Michael and Al for starting this discussion off. So what do you think? Does it really matter? Is inaudible sound going to make a difference? Discuss...