Macros: Tilt3LI, RI, LO, RO

This is a built-in Curve that tilts the power spectrum upward at +3 dB per octave. This is intended for spectra collected using a 'pink' noise stimulus, which can be created with the Daqarta Generator, or via a built-in source on some professional equipment such as recording consoles.

Pink noise has has a spectrum that falls at -3 dB per octave, which is more representative of real-world signals like music than the flat spectrum of a 'white' noise stimulus. Sound reproduction systems are thus generally designed to handle much more power at lower frequencies; if you used a flat stimulus spectrum you would need to run at very low overall power to avoid burning out the high frequency drivers, but then the low frequencies might be swamped by background sounds.

However, with a pink noise stimulus the 'perfect' system response would be a line that falls at -3 dB per octave, just like the stimulus. It is very difficult to judge how close a line comes to a particular slope, but it is trivial to compare it to the horizontal trace grid to tell if it is flat. Hence, the '+3 dB' Tilt option applies this correction for you.

This does not change your raw data in any way. The Tilt does not get saved with the data when you save to a file, with one exception: It is applied to Text (.TXT) files, which you can use for publication or presentation. For .DQA, .WAV, or .DAT files you must reapply the Tilt when you view the data.

Note that the Daqarta Pink source spectrum does not fall off at a perfect -3 dB/octave, but has several ripples of +/-0.85 dB. For critical frequency response measurements, you can create a custom mirror Curve file that will exactly match it and give perfect measurements.

Macro Notes:

Tilt3LI=1 applies a 3 dB Tilt to the Left Input, Tilt3LI=0 removes it, and Tilt3LI=x toggles between states.

Use Tilt3RI for the Right Input, Tilt3LO for the Left Output, and Tilt3RO for the Right Output.

See also Spectrum Curves Dialog, Spectrum Control Dialog

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