3 ms·
I think that most people (not teenagers) cannot hear past 15 kHz, especially with other sounds playing. This is reproducible at standard sampling rates you ment
by gugagore 10y ago
I think that most people (not teenagers) cannot hear past 15 kHz, especially with other sounds playing. This is reproducible at standard sampling rates you mention.
Harmonics are integer multiples of frequencies. Harmonics of an ultrasonic signal are even more ultrasonic. If there's any aliasing, those harmonics might map back to audible frequencies. However, no matter how cheap a speaker is, no aliasing happens. Perhaps there's another reason why an ultrasonic waveform might be audible when played through a cheap speaker, but not because of harmonics, right?
- colanderman 10y agoIt's not necessarily a function of the speaker but of the low-pass filter on the output. Unfiltered samples played back at 48 kHz will mirror the audio content at 0-24 kHz to 48-24 kHz, and repeat that pattern at every 48 kHz multiple. (This is not quite exact because DACs emit step functions, not delta functions, and slew rate comes into play, but it is a rough approximation.) This happens even if the sampled signal is a sine wave. So, any output stage after a DAC necessarily incorporates a low-pass filter to eliminate the aliasing artifacts. A cheap low-pass filter will allow these aliasing artifacts through. You can simulate this e.g. by digitally upsampling a, say, 8 kHz sampled signal to 48 kHz without any interpolation.
- Lagged2Death 10y agoHarmonics of an ultrasonic signal are even more ultrasonic. You're right. I was thinking of resonances. Even in that case, I might be wrong.