Reply To: Detecting single letters in the alphabet

[jeff-kelley]

Sure. We used the lmtool available on CMU’s website with this corpus:

A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z

zero
one
two
three
four
five
six
seven
eight
nine
ten

We got this language model:

Language model created by QuickLM on Tue Apr 26 11:48:40 EDT 2011
Copyright (c) 1996-2010 Carnegie Mellon University and Alexander I. Rudnicky

The model is in standard ARPA format, designed by Doug Paul while he was at MITRE.

The code that was used to produce this language model is available in Open Source.
Please visit http://www.speech.cs.cmu.edu/tools/ for more information

The (fixed) discount mass is 0.5. The backoffs are computed using the ratio method.
This model based on a corpus of 37 sentences and 39 words

data
ngram 1=39
ngram 2=74
ngram 3=37

1-grams:
-0.7782 </s> -0.3010
-0.7782 <s> -0.2218
-2.3464 A -0.2218
-2.3464 B -0.2218
-2.3464 C -0.2218
-2.3464 D -0.2218
-2.3464 E -0.2218
-2.3464 EIGHT -0.2218
-2.3464 F -0.2218
-2.3464 FIVE -0.2218
-2.3464 FOUR -0.2218
-2.3464 G -0.2218
-2.3464 H -0.2218
-2.3464 I -0.2218
-2.3464 J -0.2218
-2.3464 K -0.2218
-2.3464 L -0.2218
-2.3464 M -0.2218
-2.3464 N -0.2218
-2.3464 NINE -0.2218
-2.3464 O -0.2218
-2.3464 ONE -0.2218
-2.3464 P -0.2218
-2.3464 Q -0.2218
-2.3464 R -0.2218
-2.3464 S -0.2218
-2.3464 SEVEN -0.2218
-2.3464 SIX -0.2218
-2.3464 T -0.2218
-2.3464 TEN -0.2218
-2.3464 THREE -0.2218
-2.3464 TWO -0.2218
-2.3464 U -0.2218
-2.3464 V -0.2218
-2.3464 W -0.2218
-2.3464 X -0.2218
-2.3464 Y -0.2218
-2.3464 Z -0.2218
-2.3464 ZERO -0.2218

2-grams:
-1.8692 <s> A 0.0000
-1.8692 <s> B 0.0000
-1.8692 <s> C 0.0000
-1.8692 <s> D 0.0000
-1.8692 <s> E 0.0000
-1.8692 <s> EIGHT 0.0000
-1.8692 <s> F 0.0000
-1.8692 <s> FIVE 0.0000
-1.8692 <s> FOUR 0.0000
-1.8692 <s> G 0.0000
-1.8692 <s> H 0.0000
-1.8692 <s> I 0.0000
-1.8692 <s> J 0.0000
-1.8692 <s> K 0.0000
-1.8692 <s> L 0.0000
-1.8692 <s> M 0.0000
-1.8692 <s> N 0.0000
-1.8692 <s> NINE 0.0000
-1.8692 <s> O 0.0000
-1.8692 <s> ONE 0.0000
-1.8692 <s> P 0.0000
-1.8692 <s> Q 0.0000
-1.8692 <s> R 0.0000
-1.8692 <s> S 0.0000
-1.8692 <s> SEVEN 0.0000
-1.8692 <s> SIX 0.0000
-1.8692 <s> T 0.0000
-1.8692 <s> TEN 0.0000
-1.8692 <s> THREE 0.0000
-1.8692 <s> TWO 0.0000
-1.8692 <s> U 0.0000
-1.8692 <s> V 0.0000
-1.8692 <s> W 0.0000
-1.8692 <s> X 0.0000
-1.8692 <s> Y 0.0000
-1.8692 <s> Z 0.0000
-1.8692 <s> ZERO 0.0000
-0.3010 A </s> -0.3010
-0.3010 B </s> -0.3010
-0.3010 C </s> -0.3010
-0.3010 D </s> -0.3010
-0.3010 E </s> -0.3010
-0.3010 EIGHT </s> -0.3010
-0.3010 F </s> -0.3010
-0.3010 FIVE </s> -0.3010
-0.3010 FOUR </s> -0.3010
-0.3010 G </s> -0.3010
-0.3010 H </s> -0.3010
-0.3010 I </s> -0.3010
-0.3010 J </s> -0.3010
-0.3010 K </s> -0.3010
-0.3010 L </s> -0.3010
-0.3010 M </s> -0.3010
-0.3010 N </s> -0.3010
-0.3010 NINE </s> -0.3010
-0.3010 O </s> -0.3010
-0.3010 ONE </s> -0.3010
-0.3010 P </s> -0.3010
-0.3010 Q </s> -0.3010
-0.3010 R </s> -0.3010
-0.3010 S </s> -0.3010
-0.3010 SEVEN </s> -0.3010
-0.3010 SIX </s> -0.3010
-0.3010 T </s> -0.3010
-0.3010 TEN </s> -0.3010
-0.3010 THREE </s> -0.3010
-0.3010 TWO </s> -0.3010
-0.3010 U </s> -0.3010
-0.3010 V </s> -0.3010
-0.3010 W </s> -0.3010
-0.3010 X </s> -0.3010
-0.3010 Y </s> -0.3010
-0.3010 Z </s> -0.3010
-0.3010 ZERO </s> -0.3010

3-grams:
-0.3010 <s> A </s>
-0.3010 <s> B </s>
-0.3010 <s> C </s>
-0.3010 <s> D </s>
-0.3010 <s> E </s>
-0.3010 <s> EIGHT </s>
-0.3010 <s> F </s>
-0.3010 <s> FIVE </s>
-0.3010 <s> FOUR </s>
-0.3010 <s> G </s>
-0.3010 <s> H </s>
-0.3010 <s> I </s>
-0.3010 <s> J </s>
-0.3010 <s> K </s>
-0.3010 <s> L </s>
-0.3010 <s> M </s>
-0.3010 <s> N </s>
-0.3010 <s> NINE </s>
-0.3010 <s> O </s>
-0.3010 <s> ONE </s>
-0.3010 <s> P </s>
-0.3010 <s> Q </s>
-0.3010 <s> R </s>
-0.3010 <s> S </s>
-0.3010 <s> SEVEN </s>
-0.3010 <s> SIX </s>
-0.3010 <s> T </s>
-0.3010 <s> TEN </s>
-0.3010 <s> THREE </s>
-0.3010 <s> TWO </s>
-0.3010 <s> U </s>
-0.3010 <s> V </s>
-0.3010 <s> W </s>
-0.3010 <s> X </s>
-0.3010 <s> Y </s>
-0.3010 <s> Z </s>
-0.3010 <s> ZERO </s>

end

The trouble is that it’s just not accurate enough distinguishing letters. I’m very new at using OpenEars/PocketSphinx, so really I just don’t know how to approach improving accuracy.