Table of Contents
Advertisement
4 C
/
ALIBRATION
As explained in Section 2, you will need to load a calibration file before running a measurement. For speaker
measurements, the calibration file corrects for frequency response errors in the measurement microphone and
(sometimes) in the associated electronics. Headphone measurements are a bit more complicated. For EARS, you
will need two calibration files (one for each "ear"). These serve three purposes:
1. Correct the frequency response of the individual (left and right) capsules.
2. Correct for any SPL sensitivity difference between the left and right capsules.
3. Apply a compensation so that the produced measurement is "more useful" (see below).
There is more than one type of compensation that can be applied. In particular, headphones and IEMs have
different compensation types and you will get poor results if you don't use the right type.
4.1 R
AW VS COMPENSATED RESPONSE
When a measurement is made of a headphone with the EARS, the "raw" measurement tends to look something
like the green graph in Figure 11. This curve is hard to interpret, and so typically a "compensation" is applied to
produce a measurement that looks more like the graph in blue. (This is a simplified example.)
Figure 11. Simplified example of headphone raw response and compensated response
The need for compensation is a characteristic of headphone measurement rigs in general. The "right"
compensation is a topic of current and on-going research. For an accessible explanation of the topic in general,
see the innerfidelity.com article
The EARS is not an IEEE-standard ear simulator (those are very expensive). So, its compensations need to be
different from those used with expensive measurement rigs (or published in research papers). We are therefore
providing custom compensations for different uses, which can be downloaded for your set of EARS from the
EARS product page on
minidsp.com.
miniDSP Ltd, Hong Kong /
www.minidsp.com
COMPENSATION CURVES
Headphone Measurements Explained - Frequency Response Part
/ Features and specifications subject to change without prior notice
One.
21
Advertisement
Table of Contents
