Advocates Appeared:
For the Petitioners: Vishnu Mohan, N. Ramesh, R. Vetriselvi
For the Respondents: K. Srinivasan

Based on the provided legal document, the key points are as follows:

1. The legal question pertains to whether the investigation authorities can compel an accused person to give a voice sample for comparison with recorded questionable voice, especially in the context of intercepted telephonic conversations (!) (!) .

2. The court observed that the statutory provisions cited do not explicitly authorize the drawing of voice samples against the will of the accused, and the absence of specific legal provisions makes such a direction by the court unlawful (!) .

3. Drawing a voice sample is considered a physical measurement of waves emanating from the vocal cords, which is akin to a physical examination rather than testimonial evidence. Therefore, it is not protected under the right against self-incrimination (!) (!) .

4. The process of obtaining a voice sample involves measurement of sound waves, specifically frequency and intensity, which are scientific measurements and do not involve testimonial compulsion (!) (!) (!) .

5. The legal interpretation suggests that the phrase "such other tests" included in relevant statutes should be broadly and purposively interpreted to encompass voice spectrography, given the advancements in scientific techniques (!) (!) .

6. The court emphasized that since the act of obtaining a voice sample does not involve questioning or testimonial compulsion, it does not violate constitutional protections, particularly Article 20(3) of the Constitution, which guards against self-incrimination (!) (!) .

7. The court noted that the omission of voice testing in certain legislative amendments does not imply an intentional exclusion, and the methodology of voice measurement is permissible as it does not involve invasive or testimonial procedures (!) (!) .

8. Ultimately, the court dismissed the revision petitions, affirming that compelling an accused to give a voice sample for investigative purposes is lawful and does not infringe constitutional rights (!) .

9. The court reaffirmed that the investigative process involving voice measurement is a form of physical examination and falls outside the scope of testimonial evidence protected by the right against self-incrimination, provided it is conducted without invasiveness or coercion (!) (!) .

10. The decision underscores the importance of scientific techniques in modern investigations, advocating for their use while respecting constitutional protections, as long as such procedures are non-invasive and do not involve testimonial compulsion (!) (!) .

Please let me know if you need further analysis or specific legal advice based on these points.