The M4U 2’s response plot shows an extremely flat response for a headphone — one that would generally be thought to deliver too much treble. Active and passive mode measure essentially the same, while NC mode adds a max boost of 3.8 dB between 1 and 3.4 kHz.
The old ideas for speaker measurement -- i.e., +/-3 dB -- don't apply to headphones. The devices used for headphone measurement were created for measuring hearing aids. The standards for couplers used to measure hearing aids (and, more recently, in-ear monitors) are well-defined, but go up to only 10 kHz. Thus, the calibration curve provided with the equipment goes up to only 10 kHz. I'm told by G.R.A.S., the company that makes the measurement gear I use, that the industry standards for ear/cheek simulators (which attach to the coupler, and are used to measure on-ear and over-ear headphones) are rather nebulous. Thus, it's unwise to put much stock in any headphone measurements over 10 kHz. When I say that a headphone measures "flat," I'm referring to the range from about 100 Hz to 6 kHz.
I've looked it up myself. Apparently most headphones' treble do peak around 8kHz, trough around 11, and hit a final peak around 16. The M4U's 16kHz peak is a few decibels lower than "neutral", and their response falls off completely above that. This doesn't stop you from recommending them, because there's scarcely any musical content (or, for most adults, any hearing) in this frequency range.
The old ideas for speaker measurement -- i.e., +/-3 dB -- don't apply to headphones. The devices used for headphone measurement were created for measuring hearing aids. The standards for couplers used to measure hearing aids (and, more recently, in-ear monitors) are well-defined, but go up to only 10 kHz. Thus, the calibration curve provided with the equipment goes up to only 10 kHz. I'm told by G.R.A.S., the company that makes the measurement gear I use, that the industry standards for ear/cheek simulators (which attach to the coupler, and are used to measure on-ear and over-ear headphones) are rather nebulous. Thus, it's unwise to put much stock in any headphone measurements over 10 kHz. When I say that a headphone measures "flat," I'm referring to the range from about 100 Hz to 6 kHz.
I've looked it up myself. Apparently most headphones' treble do peak around 8kHz, trough around 11, and hit a final peak around 16. The M4U's 16kHz peak is a few decibels lower than "neutral", and their response falls off completely above that. This doesn't stop you from recommending them, because there's scarcely any musical content (or, for most adults, any hearing) in this frequency range.
Can you help me understand this graph? It looks like response falls off a cliff past 9kHz. Down 35db? I thought "flat" was +- 3db, roughly.