A minor suggestion for response charts in reviews

[Philosoraptor]

TL;DR: Indicate threshold of hearing on charts

Often mentioned is that higher order distortion peaks are below the threshold of hearing. I mentally draw a line around -115 dB or -120 dB.

My suggestion: have a lightly colored horizontal line at -115dB or so, maybe in gray, just to indicate right on the chart where the threshold of hearing is.

 

[staticV3]

No research exist that one could base such a threshold indicator on, and likely won't for a long time as there are no transducers that can reliably measure and reproduce HOHD of such low amplitudes.

Even if such research existed for pure tones plus harmonics, such an indicator would be misleading as consumers don't listen to sine tones and actual content (music, voice recordings etc) will drastically raise the hearing threshold due to making.

 

[DVDdoug]

No research exist that one could base such a threshold indicator on,

I'm pretty sure there is plenty of research on it, but it is "complicated" and you can't simply draw a line.

But for myself, I'd draw that "mental line" around -60dB, or maybe even -40dB for distortion. I've NEVER heard distortion from ANYTHING unless it was broken, or an amplifier was over-driven. (Or a blown or overdriven speaker.)

Noise is also tricky because we don't know the SPL level hitting the ear and noise from the speakers can be masked by other acoustic noise. In the vinyl-analog days we would have killed for a -60dB noise floor!

 

[staticV3]

I'm pretty sure there is plenty of research on it, but it is "complicated" and you can't simply draw a line.

None that confirms HOHD audibility at 115-120dB below the fundamental like OP proposes, I'm pretty sure. That was my point.

 

[Philosoraptor]

My proposal was intended to simply as a visual aid in reviews.

When a reviewer says, ". . . and that lies outside the threshold of hearing," a reference would help a newcomer understand what the reviewer meant by that.

If that cannot be done, or rather, if that wouldn't make sense to be done, perhaps Amir would add a video about this topic. It could be in depth enough for a layman but not going too far down the rabbit hole.

 

[terryforsythe]

TL;DR: Indicate threshold of hearing on charts

Often mentioned is that higher order distortion peaks are below the threshold of hearing. I mentally draw a line around -115 dB or -120 dB.

My suggestion: have a lightly colored horizontal line at -115dB or so, maybe in gray, just to indicate right on the chart where the threshold of hearing is.

It is dependent on how loud the music is playing.

Theoretically, the threshold of hearing is 0dB, though it probably varies from person to person. https://en.wikipedia.org/wiki/Absolute_threshold_of_hearing

When showing noise and/or distortion, generally it is represented as a negative dB value from the music signal reference level. As an example, I rarely listen to music over 80dB. So, I should not be able to hear any noise -80dB or lower. The instantaneous music peaks are louder, sometimes in the upper 90s, but I sincerely doubt I would hear noise from those peaks since they are transient. Even if I could, a noise level of -100dB would be sufficient to be inaudible.

EDIT: between the frequencies of 2kHz and 5kHz the threshold of hearing can be as low as -9dB SPL. So, for my example the inaudible noise levels would be -89dB, or perhaps -109dB if I was able to hear noise in transient music signals.

 

[Blumlein 88]

You can already see some issues. Some think the distortion needs to be so low in level it is below the literal threshold of hearing or roughly 0 db SPL. However that is not quite right. Generally it has been found with test tones you no longer hear distortion if it is - 60 db (.1%) or less. OTOH, it can vary with music and what makes up the music, but it is very unlikely anyone can hear at or below 1% with music (-40 db) and much music is not noticeably different until it gets beyond 3%. So not a bad idea to draw your own line at -60 db. Certainly when such distortion is -100 db and less it is below audibility. But drawing the line gets into some other factors that make where to put that line less than 100% clear nor would you get wide agreement on it.