https://www.rtings.com/headphones/tests/isolation/noise-isol...
This gives Bose QuietComfort 35 overall attenuation -27.08 dB, which is only beaten by the Sony wh-1000xm3, and some Etymotic in-ear buds.
Notably that number is more than 2x the attenuation of the Momentum, at -12.35 dB.
Usually a person won't notice an increase in volume unless it has a 3-5dB (3dB = double in power) increase. And won't perceive a double in volume without a 10dB (10dB = 10x increase in power) increase and even then it depends on the specific frequency.
Some things to check out would be: https://en.wikipedia.org/wiki/Stevens%27s_power_law https://en.wikipedia.org/wiki/Weber%E2%80%93Fechner_law (and thus Just Noticable Difference [https://en.wikipedia.org/wiki/Just-noticeable_difference])