The first two words of each curve frame contains the curve frame flags (flags 0 and 1). These flags contain information on the curve type, details about how the curve was measured or calculated, and other important data. To decipher the curve frame flags, the curve frame format must first be determined.
Bits 10-12 of flag 0 contain the curve frame format:
Value |
Description |
Data Points |
4 |
Variable Length Curve |
Variable |
Note: Number of points kept in header word 5(was
peak).
Data
Length
The number of data points in a Variable Length curve
is in header word 5(highest value)
These four non-contiguous bits of data contain the source type
used in the curve.
Value |
Description |
0 |
Pure-tone |
1 |
Composite |
2 |
Fast pure-tone with warble (FP35 only) |
5 |
Composite chirp |
8 |
Pure tone burst/pulse |
9 |
Digital speech |
11 |
Distortion chirp |
15 |
Unknown source |
The first two bits of data of flag 0 contain the distortion type
of the curve. Harmonic distortion is only measured with a pure-tone source
type.
Value |
Description |
0 |
No distortion measured |
1 |
2nd harmonic distortion |
2 |
3rd harmonic distortion |
3 |
Total harmonic distortion |
These three non-contiguous bits of data represent the software
correction factors used with the curve.
Value |
Description |
0 |
No corrections |
2 |
OES corrections |
4 |
CIC corrections |
Bit 4 of flag 0 indicates whether the reference microphone was
enabled during the measurement. The FP35 may use a reference microphone for
both coupler and real-ear measurements. The 7000 will only use a reference
microphone for real-ear measurements.
Value |
Description |
0 |
Reference microphone disabled |
1 |
Reference microphone enabled |
Bit 5 of flag 0 indicates whether the smoothing status of the
measurement. The FP35 may use a smoothing for both coupler and real-ear
measurements. The 7000 will only use smoothing for real-ear measurements.
Value |
Description |
0 |
Smoothing disabled |
1 |
Smoothing enabled |
Bits 6-7 of flag 0 indicate whether the transducer used during
the measurement.
Value |
Description |
0 |
Sound chamber |
1 |
Telecoil |
2 |
Sound field speaker |
3 |
Earphone |
Bits 8-9 of flag 0 indicate whether the source signal has been
filtered (speech weighted), and whether the measurement data is accounting for
that filter or giving raw measurement data (usually an indication of whether
the measurement data is in gain or output).
Value |
Description |
0 |
No filtering |
2 |
Source filtered, measurement data raw |
3 |
Source filtered, measurement data filtered |
Bit 13 of flag 0 indicates whether the source is leveled.
"Semi-leveled" is considered "leveled" in the curve frame.
Value |
Description |
0 |
Not leveled |
1 |
Leveled |
Bit 14 of flag 0 indicates whether the measurement curve is Gain
or SPL.
Value |
Description |
0 |
SPL (output) |
1 |
Gain (output minus input) |
Bit 15 of flag 0 and bit 5 of flag 1 indicates if the curve is
measured, computed, average, or predicted.
Value |
Description |
0 |
Measured |
1 |
Computed/difference |
2 |
Average |
3 |
Predicted |
Bit 2 of flag 1 indicates whether the curve has been modified
after it was measured or calculated..
Value |
Description |
0 |
Not modified |
1 |
Modified |
Bits 8-11 of flag 1 contain the
curve type identifier:
Value |
Description |
0 |
Response curve |
1 |
Real-ear unaided gain (REUG) |
2 |
Real-ear aided gain (REAG) |
4 |
Real-ear aided gain (REIG) |
5 |
Leveling curve |
7 |
Battery curve |
8 |
Target curve |
9 |
Audiogram curve |
10 |
Polar curve(dB vs angle) |
The curve sub-type values vary depending upon the curve frame format
and the curve type identifier. Curve types Response (0), REUG (1), REAG (2),
REIG (4), Polar(10) have the following
sub-types:
Value |
Description |
0 |
Unknown |
1 |
Flat weighted |
2 |
ANSI weighting |
3 |
ICRA weighting |
4 |
UWO child LTASS |
5 |
Cox & Moore adult LTASS |
7 |
ANSI 92 weighting |
8 |
X-Axis list |
9 |
Measurement Delay list |
Curve types Targets (8) have the following sub-types:
Value |
Description |
0 |
NAL-R |
1 |
POGO |
2 |
Berger |
3 |
1/3 Gain |
4 |
1/2 Gain |
5 |
2/3 Gain |
6 |
DSL linear |
7 |
DSL WDRC |
8 |
NAL-NL1 |
14 |
Other |
15 |
Direct |
Original Flag Inventory:
Flag 0: Bit 0(Source type), Bits 1-2(Distortion type), Bit 3(Correction factors),
Bit 4(Ref Mic), Bit 5(Smoothing), Bits 6-7(Transducer), Bits 8-9(Filtering),
Bits
10-12(Curve frame format), Bit 13(Leveling status), Bit 14(Gain status), Bit
15(Curve reference).
Flag 1: Bit 0(Correction factors), Bit 1(UNDEFINED), Bit 2(Modified), Bits
3-4(Source type), Bit 5(Curve reference), Bit 6(Source type), Bit 7(Correction
factors),
Bits
8-11(Curve type ID), Bits 12-15(Curve subtype).
New Flag Inventory:
No changes.