Expert in forensic acoustics and recording authentication
The technical supervision of this project is being carried out by José Luis Jurjo, a senior telecommunications engineer, member number 5,531 of the Official Association of Telecommunications Engineers, who has been practicing professionally since 1995.
At K2 Ingenieros, we prepare forensic audio-acoustic expert reports to analyze audio and video recordings, verify their integrity, assess their quality, prepare transcripts, and provide technical support for the evidence in court.
We represent attorneys, businesses, and individuals in civil, criminal, labor, commercial, and family law matters. We handle cases throughout Spain from our offices in Madrid, Barcelona, Lugo, and Marbella.
Would you like to submit recordings as evidence in court?
We’ll evaluate your case with no obligation and develop the best strategy for presenting it to the judge.
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What is forensic acoustics?
Forensic acoustics is the technical field that studies sound, recordings, audio systems, recording devices, and audiovisual files when they may be relevant to legal proceedings, investigations, or litigation.
Its purpose is to provide an independent technical assessment of a recording: its quality, intelligibility, continuity, origin, possible alterations, transcription, and playback conditions.
Forensic Acoustics Services
At K2 Ingenieros, we can assist with all the necessary steps to provide a recording as evidence or to conduct a technical analysis of a recording submitted by another party.
- Analysis of the authenticity and integrity of audio and video recordings.
- Detection of potential cuts, edits, discontinuities, or tampering.
- Analysis of metadata and technical characteristics of the original file.
- Temporal analysis of the oscillogram and signal continuity.
- Frequency analysis of the audio recording, voice formants, noise, and background elements.
- Assessment of the intelligibility of recorded conversations.
- Improve audio quality whenever possible and methodologically justifiable.
- Transcripts of conversations relevant to the proceedings.
- Expert audio report to be submitted to the court.
- Confirmation and defense of the expert report at trial.
Do you need to evaluate a recording or prepare an expert report?
We can review the file, assess its technical value, and advise you on the most appropriate type of analysis or report for your situation.
Is it admissible to submit a recording as evidence in court?
Recordings can be highly valuable as evidence when they capture conversations or events relevant to the litigation. A clear recording that is properly submitted can help establish disputed facts, facilitate a settlement, or strengthen the litigation strategy.
Whether a recording is admitted and evaluated as evidence always depends on the specific case, how it was obtained, its relevance to the proceedings, and the court’s discretion. From a technical standpoint, the expert report helps assess aspects such as the authenticity, integrity, quality, intelligibility, and traceability of the file.
Experience and technical expertise
K2 Ingenieros has been providing professional services in engineering, acoustics, and technical expert assessments since 1995, with more than 850 projects certified by the Official Association of Telecommunications Engineers.
The technical supervision of the forensic acoustics work is being carried out by José Luis Jurjo, who holds a degree in telecommunications engineering from the Polytechnic University of Catalonia (specializing in electronics), an MBA from ESADE, and is a member of the Official Association of Telecommunications Engineers.
His career combines expertise in acoustics, telecommunications, digital signal processing, software, databases, and artificial intelligence. He has worked at Hewlett Packard on the development of software and real-time intelligent printing systems, has served as an associate professor at the UPC, and has been working as a freelance professional since 1998.
In the field of forensic expertise, we have been involved in numerous legal disputes related to the authentication of recordings, the identification of speakers, the analysis of sound sources, the assessment of intelligibility, the detection of potential tampering, and expert opinions on the types and characteristics of recording devices.
José Luis Jurjo is also the co-author of three international patents in the field of technology and electronics, and a member of professional and technical organizations such as the Catalan Association of Telecommunications Engineers, the Free Software Foundation, and ResearchGate.
Steps for submitting a recording to the court
For a recording to be admissible as evidence, simply submitting an audio or video file is not enough. The evidence should be prepared in a well-organized and technically sound manner.
1. Keep the original file
Whenever possible, the original source of the recording should be preserved: cell phone, voice recorder, camera, video surveillance system, downloaded file, or storage medium.
2. Assess quality and intelligibility
A recording with background noise, poor quality, overlapping voices, or insufficient volume may have limited evidentiary value. Before preparing the report, we assess whether the conversation is intelligible and what technical limitations it has.
3. Prepare an accurate transcript
The transcription must be accurate, clearly identifying speakers, pauses, inaudible sections, and relevant parts.
4. Verify the integrity of the recording
Forensic analysis makes it possible to determine whether there are signs of cuts, edits, discontinuities, sudden changes in background noise, temporal alterations, or subsequent modifications to the file.
5. Issue the expert report
The report must clearly explain the methodology used, the tools employed, the technical limitations of the analysis, the results obtained, and the expert conclusions in a manner that is defensible in court.
6. Present the evidence at trial
If necessary, the expert witness may present the report and answer questions from the parties, clarifying the methodology, the results, and the actual scope of the technical conclusions.
Technical analysis of the recording
A thorough forensic analysis must cover the various aspects of audio analysis. It is not merely a matter of listening to the recording, but of examining the file, its signal, its technical characteristics, and any potential inconsistencies.
- File metadata: format, encoding, dates, software, source device, and any transformations.
- Critical listening: technical evaluation of voices, noises, background sounds, interruptions, compression, and other relevant acoustic elements.
- Temporal analysis: examination of the oscillogram, signal continuity, cuts, silences, transitions, and level changes.
- Frequency analysis: study of the spectrum, voice formants, background noise, frequency bands, filtering, and discontinuities.
- Acoustic context: stage, distance, reverberation, overlapping voices, microphone, and recording conditions.
Source and chain of custody of the recording
The source of the recording is a key factor. Analyzing an original file extracted from the device is not the same as analyzing compressed audio that has been forwarded, downloaded from an app, or converted to another format.
Whenever possible, we recommend keeping the original file and avoiding forwarding, cropping, or converting it before analysis.
Analysis of manipulated or AI-generated recordings
The emergence of advanced editing tools and AI-powered voice synthesis makes it increasingly important to conduct a thorough and well-documented technical analysis.
At K2 Ingenieros, we analyze signs of editing, cuts, repeated compression, temporal inconsistencies, alterations to metadata, changes in background noise, and other factors that may affect the technical and evidentiary value of a recording.
Transcription of court recordings
We can prepare full or partial transcripts, identify speakers whenever possible, mark inaudible sections, and highlight pauses, interruptions, overlapping speech, or other details relevant to the interpretation of the audio.
Presentation of the expert report at trial
During trial testimony, the expert witness may explain the methodology used, the tools employed, the conclusions reached, and the limitations of the analysis. The expert may also respond to objections raised by the opposing party regarding the quality, authenticity, integrity, or interpretation of the recording.
Forensic acoustics experts throughout Spain
From our offices in Barcelona, Madrid, Lugo, and Marbella, we handle expert witness assignments throughout Spain. We can work with digital documents, audio and video files, original devices, or through technical meetings with attorneys and clients.
Request a technical evaluation of your recording
If you have a recording that you need to submit, analyze, or challenge in legal proceedings, we can review the case, assess the quality of the file, and recommend the most appropriate type of expert report.
Frequently Asked Questions About Forensic Acoustics
Is a recording admissible as evidence in court?
It depends on the specific case, how it was obtained, its relevance to the proceedings, and the court’s discretion. From a technical standpoint, an expert report can help assess its authenticity, integrity, quality, and intelligibility.
Do I need an expert report to submit an audio recording?
It is not always required, but it is generally recommended when the recording is subject to dispute, when its origin is questioned, or when it is necessary to technically verify its content, quality, or lack of tampering.
Is it possible to tell if a recording has been tampered with?
In many cases, it is possible to analyze evidence of editing, cuts, discontinuities, changes in background noise, successive compressions, or alterations to metadata.
Can you transcribe a recording for use in court?
Yes. We can provide full or partial transcripts, marking inaudible sections, interruptions, overlapping voices, and other relevant elements.
Is a WhatsApp or phone recording acceptable?
It may be usable, but you should check its source, format, compression, any forwarding history, and the availability of the original file.