N4 NATO Native and Non-Native Speech

Item Name: N4 NATO Native and Non-Native Speech
Author(s): John Grieco, Laurent Benarousse, Edouard Geoffrois, Robert Series, Herman Steeneken, Hans Stumpf, Carl Swail, Dieter Thiel
LDC Catalog No.: LDC2006S13
ISBN: 1-58563-344-5
ISLRN: 632-458-830-271-0
DOI: https://doi.org/10.35111/rz1e-1575
Release Date: April 17, 2006
Member Year(s): 2006
DCMI Type(s): Sound
Sample Type: pcm
Sample Rate: 16000
Data Source(s): microphone speech
Application(s): cross-lingual information retrieval, sociolinguistics, speaker verification, speech recognition
Language(s): Dutch, English, German
Language ID(s): nld, eng, deu
License(s): LDC User Agreement for Non-Members
N4 NATO Native and Non-Native Speech Agreement
Online Documentation: LDC2006S13 Documents
Licensing Instructions: Subscription & Standard Members, and Non-Members
Citation: Grieco, John, et al. N4 NATO Native and Non-Native Speech LDC2006S13. Web Download. Philadelphia: Linguistic Data Consortium, 2006.
Related Works: View


N4 NATO Native and Non-Native Speech was developed by the NATO research group on Speech and Language Technology and contains approximately 9.5 hours of recorded multilingual speech and associated transcripts. The corpus was created to provide a military-oriented database for multilingual and non-native speech processing studies.

Speech technology is covering an increasing number of languages, and systems are becoming more robust with regard to speech variability such as speaking style and accents. However, for real applications, especially in a multilingual and multinational context, further robustness to regional and even non-native accents is necessary. Among the numerous corpora available for speech research, few have specifically addressed this issue.

The NATO Speech and Language Technology group decided to create a corpus geared towards the study of non-native accents. The group chose naval communications as the common task because it naturally includes a great deal of non-native speech and because there were training facilities where data could be collected in several countries.


The database was collected in four countries (Germany, The Netherlands, United Kingdom, and Canada) during naval communication training sessions in 2000-2002. For each country, the main part of the recordings consists of a NATO Naval procedure in English where the typical sentence sounds like "This is alpha, whiskey, roger. I make two seven zero six hostile, two seven zero six. Out." In addition each speaker read a text, "The North Wind and the Sun," in English and his or her native language.

The audio material was recorded on DAT and downsampled to 16 kHz, 16 bit. All the audio files have been manually transcribed and annotated with speakers' identities using the tool Transcriber. Navy procedure recordings and text readings have been stored in different files. The first digit in the filename indicates the type of speech

Among speech segments, the duration of Navy procedure recordings range from 1.3 to 2.3 hours for a total of 7.5 hours. The duration of the native language text readings range from 1.5 to 22.9 minutes for a total of approximately one hour.

Signal 5.30 3.20 5.00 6.30 19.80
Silence 3.00 0.56 2.00 4.70 10.26
Speech 2.30 2.64 3.00 1.60 9.54
Speech 2.30 2.64 3.00 1.60 9.54
Navy proc 2.00 1.90 2.30 1.30 7.50
Read text 0.30 0.74 0.70 0.30 2.04
Read text 0.30 0.74 0.70 0.30 2.04
Non-native 0.27 0.37 0.32 0.00 0.96
Native 0.03 0.37 0.38 0.30 1.08

The database contains the following information about each speaker: gender, age, weight, length, possible speaking or hearing disorders, education level, living area, accent, second language, the year English was learned (for non-native speakers). The speaker accents vary widely from country to country. The speakers' average age was 22.6 years. Nineteen women participated, accounting for 18% of the study participants. There were a total of 115 speakers.

#Speakers 22 51 31 11 115
#Women 5 0 9 5 19
Age 22-35 17-23 17-61 19-62 17-62
Age mean 28.3 20.1 21 27.5 22.6


For an example of the data in this corpus, please listen to this audio sample (SPH) and view this transcript sample (TRS).


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