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 |
Generic |
Variable |
Data Length
The number of data points in a generic curve is the
packet length minus 9. (Or 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 |
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 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 8-12 of flag 1 contain the curve type identifier:
Value |
Description |
0 |
Coupler curve vs freq |
1 |
Probe curve vs freq |
2 |
Distortion vs freq |
3 |
I / O vs input SPL |
4 |
Leveling curve vs freq |
5 |
Battery curve vs freq or input SPL |
6 |
Target curve vs freq |
7 |
Audiogram curve vs freq |
8 |
Polar curve vs angle |
9 |
dB or Linear vs time |
10 |
|
11 |
|
The curve sub-type values vary depending upon the curve frame format and the curve type identifier.
Curve type Coupler (0) has 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 |
Telecoil(unleveled & unweighted) |
9 |
Frequency List |
Curve type Probe (1) has 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 |
Earphone (unleveled &
unweighted) |
9 |
Frequency List |
Curve type Distortion(2) has the
following sub-types.
Value |
Description |
0 |
No distortion measured |
1 |
2nd harmonic distortion |
2 |
3rd harmonic distortion |
3 |
Total harmonic distortion |
4 |
Frequency List |
Curve type I/O(3) has the following
sub-types.
Value |
Description |
0 |
dB response |
1 |
Input SPL list |
Curve type Leveling (4) has the following
sub-types:
Value |
Description |
0 |
Frequency List |
1 |
Leveling factor |
Curve type Battery(5) has the following
sub-types:
Value |
Description |
0 |
Current draw vs freq |
1 |
Current draw vs level |
2 |
Freq list |
3 |
Input SPL list |
Curve type Targets (6) has 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 |
13 |
Frequency List |
14 |
Other |
15 |
Direct |
Curve types Audiogram (7) have the
following sub-types:
Value |
Description |
0 |
dB Response |
1 |
Frequency List |
Curve type Polar (8) has the following
sub-types:
Value |
Description |
0 |
dB Response |
1 |
Angle List |
Curve types Time domain (9) have the
following sub-types:
Value |
Description |
0 |
dB Response |
1 |
Linear Response |
2 |
Time List |
Note: This includes R/A(dB),
EDSP(linear), etc.
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:
Flag 0: Bit 0(Source type), Bits 1-2(Available), Bit 3(Correction factors), Bit 4(Ref Mic), Bit
5(Smoothing), Bits 6-7(Available), 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).
Notes from Aaron: Reallocate Flag 0 bits 1-2 for source filter?