AUGUST 2019 MACWORLD 105
When listening to speakers in
a room, the high frequencies
are directional, while
the low frequencies are
omnidirectional, resulting
in more reflections from
the room boundaries and
thus tending to emphasize
the bass. PSB’s RoomFeel
technology aims to simulate
this effect in the M4U 8.
onboard DAC (digital-to-analog converter),
amplifier, and active noise cancellation (ANC).
This function uses four microphones in the
headphones to sample ambient sounds that
are phase-inverted and mixed with the
original to reduce their level by means of
phase cancellation. When the onboard power
amp is active (with or without ANC), pushing a
button engages Transparency Mode, which
temporarily drops the audio by 30dB and
amplifies ambient sounds so you can hear
the outside world.
One important feature is PSB’s RoomFeel
technology, which is engaged when the
power amp is active with or without ANC.
Based on research performed by PSB and
Harman, RoomFeel simulates the sonic
signature of high-end speakers in a good
listening room, which tends to emphasize
lower frequencies because of omnidirectional
reflections and roll off higher frequencies
because they are more directional with fewer
reflections. According to the M4U 8
datasheet, RoomFeel will “Take away the
room and the music sounds limited to the
space between your ears with an unnatural
emphasis to the treble. RoomFeel opens up
the soundstage while adding natural warmth
to the sound.” We shall see.
The M4U 8’s four microphones are also
used to answer calls on your mobile
phone. If you receive a call while listening,
hit a button, and the music pauses while
you answer the call. Once you’re done, hit
the button again to resume playback.
Unlike some wireless headphones, the
M4U 8 still act as passive cans if the batteries
are drained or you wish to conserve them by
keeping the power off. In that case, you must
connect an analog cable to the source, and
there is no ANC, Bluetooth, or RoomFeel.
Still, I heartily welcome this feature for those
times when the batteries are dead and
there’s no AC outlet to charge them.
USER INTERFACE
The controls are found on the back of the
right earcup. Starting at the top, the