Sentiamo i Megahertz
Inviato: 15 set 2015, 19:51
Da un dettagliato studio di Milind N. Kunchur pare che la soglia di udibilità temporale minima sia di 6 microsecondi:
The result presented here has relevance for the perfor-
mance requirements of audio components and digital en-
coding schemes. It is known that the bandwidth require-
ment for sonically transparent audio reproduction is higher
than the 20 kHz: in the coding of digital audio it has been
noted (Stuart, 2004) that listeners show a preference for a
96 kHz sampling rate over the CD (digital compact disk)
standard of 44.1 (i.e., a 22 kHz Nyquist frequency). It
is sometimes thought that this may be due to the less
drastically sloped cutoff of the digital filter and the re-
duced disturbances introduced in the audible pass band
The present work shows that the bandwidth requirement
into the ultrasonic range is more fundamental and not just
due to artifacts of digital filtering. It is also commonly
conjectured in the audio literature that the time-domain
response of a system (e.g., temporal smearing caused by
capacitive and other energy-storage mechanisms in cables)
is a key factor in determining the transparency of repro-
duction (see, for example, van Maanen, 1993).
In a sister experiment (Kunchur, 2007), where signals were temporally altered by spatial displacement of speakers instead of by electronic means, a similar threshold of 6μs was found. That work also makes a rudimentary neurophysiological estimate for the temporal resolution for transient stimuli that is in the 2–16μs range.
http://boson.physics.sc.edu/~kunchur/temporal.pdf
The result presented here has relevance for the perfor-
mance requirements of audio components and digital en-
coding schemes. It is known that the bandwidth require-
ment for sonically transparent audio reproduction is higher
than the 20 kHz: in the coding of digital audio it has been
noted (Stuart, 2004) that listeners show a preference for a
96 kHz sampling rate over the CD (digital compact disk)
standard of 44.1 (i.e., a 22 kHz Nyquist frequency). It
is sometimes thought that this may be due to the less
drastically sloped cutoff of the digital filter and the re-
duced disturbances introduced in the audible pass band
The present work shows that the bandwidth requirement
into the ultrasonic range is more fundamental and not just
due to artifacts of digital filtering. It is also commonly
conjectured in the audio literature that the time-domain
response of a system (e.g., temporal smearing caused by
capacitive and other energy-storage mechanisms in cables)
is a key factor in determining the transparency of repro-
duction (see, for example, van Maanen, 1993).
In a sister experiment (Kunchur, 2007), where signals were temporally altered by spatial displacement of speakers instead of by electronic means, a similar threshold of 6μs was found. That work also makes a rudimentary neurophysiological estimate for the temporal resolution for transient stimuli that is in the 2–16μs range.
http://boson.physics.sc.edu/~kunchur/temporal.pdf