Frequency response, Important – Dayton Audio OmniMic V2 Precision Measurement System User Manual
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Frequency Response
Use the Frequency Response analyzer to measure the frequency response or the impulse
response.of a sound system.
Important!
To use this properly you must be playing the specified audio track (from the OmniMic
test track CD or DVD) as indicated at the top of the program window. The measurement
is matched to the test signals provided on the specified tracks. You can choose to use between two
types of signal by selecting between the "pseudo noise" and "sine sweep" buttons above the graphs.
"Pseudo-noise" test signals, that sound like Pink Noise are easy on the ears for extended
sessions. The accuracy using pseudo-noise at highest frequencies, however, can be
degraded by sample clock variations
.
Sine Sweep signals provide the cleanest and most accurate measurements, as well as being
able to drive speakers at specific SPL levels. This is the preferred choice for frequency
response measurements and should be used for all high-frequency measurements
Frequency Response measurements will not operate correctly if you try to use normal Pink
Noise test signals or any signal other than the one specified on the program window! The
timing and spectral content of the files are critical for proper operation of OmniMic's
synchronous frequency response measurement system.
Doing a Frequency Response measurement with OmniMic is easy -- essentially, you just play
one of the proper Tracks, as indicated near the top of the form, set the microphone to pick up
your system and the graph is shown on the screen. The OmniMic software also allows many
adjustements which you can use to customize the graph or measurement. For
more
see the help section on that topic.
About Frequency Responses
Frequency Response is a curve that shows how strongly an audio system reproduces
different parts of the frequency range. The curve will be higher on the graph at frequencies
where the system plays louder, and lower (perhaps showing only varying background noise) at
frequencies where the system plays weaker or not at all.
A perfect Frequency Response curve would look like a flat line over all frequencies. A
typical one, though, will have variations of from 3 to 30 decibels ("dB") over most of the
frequency range, and often dropping off at very low bass frequencies.
You can measure near individual speakers (about 1 meter away is best), or out in the room at
various listening positions. The frequency response of a loudspeaker will be different at
different places in the room. You can also use OmniMic to make an ongoing "average
curve" over multiple position
give a typical frequency response curve.
A frequency response is related to its "impulse response" (the pressure signal that a
speaker or sound system would make if it were fed by an extremely short pulse). OmniMic can