Bruker denne målingen kun mellom 250 og 4Khz.
Jeg tolker det som at du har et litt livlig rom slik høyttalerene spiller i rommet nå og uten kompensering med target kan det lyde litt lyst spesielt ved 2-4Khz.
I store rom som ditt synes jeg dette ofte kan gi en lettflytende signatur i toppregisteret som kan likne den lyden man hører live, men hvis man har problemer i området 800-4Khz kan en slik decay forsterke problemene og gi en lys og spiss lyd på vanskelige innspillinger.
Legger denne standarden til grunn.
D: Midrange Decay Times
Standards:
• Time taken for sound to decay 60dB (T60) should be between 0.2s and 0.5s from 250Hz
to 4kHz
• T20 and T30 should be +/25%
across the same frequency band using one third octave
smoothed bands.
Single figure T60 measurements cannot do much more in a small room than tell you whether a room is
overly live or overly dead. More useful is to look at how sound decays across the critical midrange
frequency bands from 250Hz to 4kHz and to examine whether the speed of this decay is consistent over
time. There are four different problems that can exist with decay times – they can be too long, too
short, uneven across the frequency spectrum or vary excessively over time.
Overly long decay times can obscure low level detail and the timbre of a voice or instrument in much the
same way as a room with a high noise floor. A room with a long decay times also tends to sound harsh
and brittle and can be an unpleasant place to listen resulting in rapid fatigue. Overly long decay times
are considered those over 0.5s.
Decay times that are too short may not allow a spacious, enveloping soundstage to develop and
therefore can be quite boring places to listen. Overly short decay times are considered those under 0.2s.
Music does not come to life but rather sounds dry and sterile. Of note is the fact that acoustical
diffusors actually yield absorption effects in the process of dispersing energy. This is important as a
space with ample use of an appropriate type of diffusor may have a decay time on the lower range but
not feel dry/sterile (likely just the opposite!). This is a prime example of the nuanced nature of
acoustical control where the “road you take” to a specific measurement result is every bit as important
as the end measurement.
A room that exhibits uneven decay characteristics, where the sound decays much faster at some
frequencies than others can at worst sound noticeably unbalanced with a ‘dull’ treble or ‘bloated’ bass.
Uneven decay is most often caused by furnishings within the room such as thin drapes and carpets that
absorb significantly more energy at treble frequencies (above around 1kHz) than they do at midrange
frequencies. Providing the energy follows the criteria in Section B of this document, it is actually
preferred to retain upper midrange and high frequency energy. Our target here is for T20 and T30 to be
within +/‐25% across the frequency spectrum. Significant changes in decay time from T20 through T60
are also a good indicator of spectrally unbalanced reflected sounds.