Forensic Speaker Identification

Forensic Speaker Identification Quiz crafted by-

Dr. Poonam Singh

Scientific Officer, 

Assistant Chemical Examiner for Government of M.P. 

Regional Forensic Science Laboratory, Bhopal (M.P).

INTRODUCTION TO FORENSIC SPEAKER IDENTIFICATION

In the present era, widely available facilities of telephones, mobiles and tape recorders results in the misuse of the device and thus, making them an efficient tool in commission of criminal offences such as extortion, blackmail threats, kidnapping, anonymous calls, harassment calls, ransom calls, terrorist calls, match fixing etc. The criminals has seen the possibility for misuse of the various modes of communication of voice, believing that they will remain incognito, and thus, nobody would recognize them. It is fortunately no longer true as “A voice is much more than just a string of words.”

Forensic speaker identification is the application of science which helps to solve the problems related to identification of the unknown speaker in criminal investigation. It is based on the theory that the voice of each person is as unique as fingerprints or DNA. Voice of an individual depends on the features of organs such as vocal tract shape, cavity of the mouth, pronunciation skills, regional accent, etc. which place a significant role in identifying speaker. Forensic Experts are able to form a definite opinion when the voice is normal, but problem arises when they have to deal with the disguised voice samples including accidental as well as intentional. 

Let’s look at the questions and their answers:

Que 1. What is speech verification used for?

a) Differentiating between live people and digital voices

b) Reducing fraud and identity theft

c) Identifying languages

d) Eliminating need of dial pad input

Answer- b) Reducing fraud and identity theft

Que 2. How does emotional state of human being affect the speaker voice comparison process?

a) Has a considerable impact on his speech.

b) No impact on speech

c) Directly affects the basis of speaker voice comparison process.

d) (a) and (c) both

Answer- d) (a) and (c) both

Que 3. Structure that separate the Oral and Nasal cavity 

a) Alveolar ridge

b) Palate

c) Mandible

d) Tongue

Answer- b) Palate

Que 4. What kind of signal is used in speech recognition?

a) Electric Signal

b) Electromagnetic Signal

c) Acoustic Signal

d) RADAR

Answer- c) Acoustic Signal

Que 5. Sounds that are produced with an unobstructed open vocal tract:

a) Consonants

b) Vowels

c) Plosives

d) Diphthongs

Answer- b) Vowels

Que 6. Voiceless sounds are produced when:

a) Vocal cords are stationary

b) Vocal cords are vibrating

c) Vocal folds are joined together

d) None of above

Answer- a) Vocal cords are stationary

Que 7. Study of Sounds of various language is known as:

a) Biology

b) Phonology

c) Philately

d) Physiology

Answer-b) Phonology

Que 8. The process of ageing leads to change the voice over the long-term because of?

a) Vocal tract and related organs are subject to gradual deformation

b) Muscle strength of the tongue declines with ageing

c) the speaking rate reduces with ageing due to cognitive decline 

d) All of above

Answer- d) All of the above

Que 9. Pharynx is an important structure in determining -----of speech

a) Nasality

b) Resonance

c) Intensity

d) Frequency

Answer- b) Resonance

Que 10. Rhythm of speech and intonation, stress pattern of speech are recognized as:

a) Formant formation

b) Prosody

c) Semantics

d) Morphology

Answer- b) Prosody

Que 11. Fourier series representation can be used for:

a) Periodic Signals

b) Non periodic signals

c) (a) and (b) both

d) None of above

Answer- a) Periodic Signals

Que 12. A continuous time signal can be converted into discreet time signal by-

a) Modulating

b) Sampling

c) Integrating

d) Differentiating

Answer- b) Sampling

Que 13. Voice of man is heavy compared to women because:

a) Male vocal cords are stronger

b) Male vocal cords are longer

c) The concept is not related

d) Women vocal cords are shorter

Answer- b) Male vocal cords are longer

Que 14. What is stereo?

a) Audio made up of two channels

b) Audio made up of single channels

c) Digital audio tape

d) None of the above

Answer- a) Audio made up of two channels

Que 15. Intraspeaker variation refers to:

a) Variation within voices of same speaker

b) Variation between voices of different speakers

c) (a) and (b) both

d) None of above

Answer- a) Variation within voices of same speaker