推 Falcoon:有看有推～ 03/03 03:39
推 biaw:謝謝~~! 03/05 02:21
FAQ裡面的What is diffuse-field equalisation?
https://europe.beyerdynamic.com/service/faqs.html
詳細的就不翻譯了，裡面有稍微提到beyer自家的測試環境
五面體的特製回聲室搭配一個八面體的揚聲器
文中也偷偷表了HD800的那個各別"頻率響應平坦認證"一下 XD
耳機廠現在越來越肯講實話了，好現象
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What is diffuse-field equalisation?
Have you ever wondered why a frequency response curve is almost never
included with headphones? I can let you in on the secret: they look terrible!
Such an erratic frequency response graph would hardly encourage customers to
make a purchase. What the customer wants in the end is something that is
linear. Uncoloured. Solid.
But why do these frequency response curves look so horrible? And why do
you not clearly hear these glaring leaps and drop-offs?
How we hear
From childhood on, humans are accustomed to perceiving acoustic events.
We grow up with a variety of sound sources and get used to them. The baby
rattle, the clatter of dishes from the kitchen, pedestrians on the street,
music from loudspeakers, etc. – all of these sound sources have something in
common: they are located relatively far from the ear.
Before the sound from these sources reaches our eardrum, it is coloured
by the shape of our head and our ear. Depending on the angle, many
frequencies are accentuated and others are attenuated. With time, we learn
these frequency patterns and are able to do things such as recognise the
direction in which the sound source is located. Therefore, we do not hear
sound as it was produced at the source, but instead in coloured form.
Loudspeakers and headphones
When we listen to music over loudspeakers with a linear frequency
response curve, we are actually hearing a spectrum that is influenced by the
distinctive shape of our head. We perceive this as linear.
When listening with headphones, the headphones do not even try to
generate any effects on the outer ear, since the sound source is so close to
the ear. What comes out of the headphones arrives at the eardrum in
relatively uncoloured form. In order for the headphones to still sound
natural, the sound must be coloured so that it is as similar as possible to
the colourations caused by the shape of the head and ear. In other words, the
headphones must have the frequency response set so that it sounds like the
sound is coming from a distant source.
Diffuse-field equalisation
In order to adjust headphones to our listening habits, we must first use
technical means to measure the colourations caused by our head. For example,
an artificial head with microphones in the ears is used. When this artificial
head is exposed to sound, you can use the microphones to measure how the
sound would be perceived by us instead of the artificial head.
So that the headphones do not have a sound that always seems to come from
one direction, but instead can reproduce all sound directions equally, the
artificial head must be exposed to sound from many directions and the result
averaged. This does not perfectly reproduce any direction perfectly, but no
direction is completely suppressed.
At beyerdynamic, there is an echo chamber for this purpose. It is a
small, five-sided room with acoustic sails on the ceiling that looks quite
bare and empty. The fascinating thing about it is that, although it is the
size of child’s room, it sounds like a cathedral! An octahedron loudspeaker
that radiates sound in eight directions is in one corner. If you are far
enough away from the loudspeaker, the strong echo causes you to no longer be
in the direct field, but instead in the diffuse field of the loudspeaker,
i.e. the area in which the sound reflected off the walls is louder than the
sound that is coming directly from the loudspeaker.
If artificial head measurements are carried out in this chamber, many
sound directions overlap due to the echo, allowing us to obtain the required
averaging. This averaging (the measurement in the diffuse field) gives
diffuse field equalisation its name.
In order to equalise the headphones, they are placed on the artificial
head and the frequency response is adjusted so that the measured frequency
behaviour corresponds to that of the diffuse field.
Discussion
Since the mechanical and electronic options for changing the frequency
response of headphones are limited, the equalisation cannot be carried out
perfectly. Different headphones are also adjusted to various tastes. It is by
no means the case that all diffuse-field equalised headphones sound the same.
In addition, the frequency patterns for directional hearing depend on the
shape of the head and ears. For this reason, they are a little different for
everyone. Hence, measuring with an artificial head is a pretty arbitrary
choice.
Diffuse-field equalisation is therefore an important part of improving
localisation with headphones and avoiding “in-head localisation”, but it is
not guaranteed to work and is no replacement for extensive test listening.
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※ 編輯: takase 來自: 1.170.198.101 (03/02 14:20)