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Audio Forensic Examination: Integrity, Cuts and Cloned Voice

Spectral and continuity analysis to establish whether a recording is authentic and unaltered.

Recordings of conversations are commonly used as evidence, but a well-made cut can change the meaning of everything. The forensic examination analyzes the spectrogram, background noise, signal continuity and acoustic coherence to detect edits, and evaluates indicators of voice synthesis when AI cloning is suspected.

Spectral and waveform analysis
Detection of cuts and splices
Verification of background noise continuity
Indicators of synthetic or cloned voice
Improved intelligibility where possible
Report ratifiable in court
Instant WhatsApp OR CALL US 930 485 101
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Request: Audio Validation
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Law 11/2023
The same legal validity as signing in person
Registered
Practising notaries of the Notarial Association of Spain
4,7 / 5
Average rating from more than 1.000 clients
< 2 h
Average response time to a request

When might you need it?

The most common cases for this procedure

Recording of conversations
Recordings of one's own conversations submitted as evidence, whose integrity is disputed by the other party.
Business calls
Telephone contracts or cancellations denied by the company.
Threats and coercion
Voice notes and calls with intimidating content.
Cloned-voice scams
Calls in which a family member's or executive's voice is impersonated.
REQUIREMENTS FOR THIS PROCEDURE
Provide the original file in its native recording format, without recompressing
Recording your own conversations is lawful; recording other people's conversations in which you do not take part is not
Do not apply filters or normalize the audio before the examination
Indicate the specific segment and what needs to be established
DOCUMENTS YOU WILL NEED
01Original audio file (device's native format)
02Device or app used for the recording, if available
03Identification of the participants and context of the recording
04Timestamps of the relevant segments
REGULATIONS: Spanish Civil Procedure Act (LEC), arts. 299 and 382 STC 114/1984 and case law on recording one's own conversations Art. 197 Criminal Code (limits on recording third parties) ISO/IEC 27042

How does the process work?

From request to signed document, with no travelling

1 Forensic acquisition 2 Spectral analysis 3 Edit detection 4 Report and ratification
1
Forensic acquisition
⏱ 24 hours
Hash-verified copy of the original file; the analysis is never performed on the working file.
2
Spectral analysis
⏱ 24-48 hours
Spectrogram, waveform, background noise continuity and room response.
3
Edit detection
⏱ 48 hours
Splices, anomalous silences, encoding changes and indicators of synthetic voice.
4
Report and ratification
⏱ 48-72 hours
Expert report with spectral graphs, transcript if applicable, and availability for court appearance.

Clients who have already done it

Verified reviews of this service

4,7★★★★★
★★★★★ES
"La compañía negaba mi cancelación por teléfono. El peritaje acreditó la grabación íntegra y sin cortes. Me dieron la razón."
FJ
Fernando J.
Contrato telefónico · Sevilla
★★★★★ES
"Las notas de voz eran clave y él decía que estaban manipuladas. El informe demostró que eran continuas y auténticas."
BL
Beatriz L.
Coacciones · Alicante
★★★★★EN
"A cloned voice call almost cost my company a large payment. The audio report identified clear synthesis markers. Excellent technical work."
SW
Simon W.
Voice cloning · Madrid
★★★★★ES
"Necesitaba acreditar que la grabación aportada por la otra parte estaba recortada. El peritaje localizó el empalme exacto."
AT
Ana T.
Familia · Valencia
★★★★★ES
"Necesitaba el trámite con urgencia y lo resolvieron en tiempo récord. El notario fue muy profesional y recibí el documento al día siguiente."
CR
Carmen R.
España
★★★★★EN
"Excellent service from start to finish. Everything was handled online and the signed document arrived within 24 hours. Highly recommended."
JW
James W.
Reino Unido
★★★★★ES
"Lo gestioné desde Buenos Aires sin viajar a España. Me guiaron paso a paso, incluso con el certificado digital. Todo claro y sin sorpresas."
MG
Mariana G.
Argentina
★★★★★FR
"Démarche réalisée entièrement en ligne depuis Paris. Équipe très réactive sur WhatsApp et notaire très professionnel. Impeccable."
SL
Sophie L.
Francia
★★★★★ES
"El proceso fue mucho más sencillo de lo que esperaba. Atención cercana por WhatsApp y presupuesto cerrado sin costes ocultos."
AM
Andrés M.
España
★★★★★DE
"Die Beurkundung wurde komplett online erledigt. Schnelle Terminvergabe, klare Anweisungen und das Dokument kam am nächsten Tag."
KB
Katrin B.
Alemania
★★★★★IT
"Pratica completata interamente online dall'Italia. Notaio disponibile e documento firmato in 24 ore. Servizio eccellente."
MT
Marco T.
Italia
★★★★★PT
"Tratei de tudo sem sair de Lisboa. Acompanhamento constante por WhatsApp e documento entregue no dia seguinte. Recomendo totalmente."
BS
Beatriz S.
Portugal
★★★★★ES
"Desde CDMX pensé que sería complicadísimo, pero salió a la primera. Videollamada puntual, notario clarísimo y precio cerrado."
GP
Gloria P.
México
★★★★★EN
"Handled from New York without flying to Spain. Clear instructions, fast scheduling and constant updates. Five stars."
SK
Sarah K.
Estados Unidos

Frequently asked questions

How long does the audio analysis take?
The complete analysis takes between 5 and 7 business days, depending on the audio length and case complexity. In urgent situations, we can expedite the process.
How should I send the audio file?+
Send the original audio without editing or re-encoding, in the original recording format (WAV, M4A, MP3, etc.). Use secure transfer platforms. DO NOT send it via WhatsApp as it compresses the audio.
Can you identify who is speaking in the audio?+
Yes, through biometric voice analysis we can compare the recording with known voice samples and determine if they match with a high degree of probability.
Can you detect audio generated by artificial intelligence?+
Yes, we use specialized technology to detect AI-cloned voices. We analyze breathing patterns, micro-pauses, digital artifacts, and other characteristics that reveal synthetic voices.
Can you detect if the audio has been cut or edited?+
Yes, through spectral and metadata analysis we can identify cuts, insertions, deletions, speed changes, and other manipulations.
Is the report valid in court?+
Yes, our reports have full legal validity. Forensic experts can ratify the analysis in court and technically explain the conclusions.
Can you improve the audio quality to hear it better?+
Yes, we can perform forensic audio enhancement by removing background noise and improving intelligibility, always preserving the integrity of the original evidence.
How much does the service cost?+
The price depends on the audio length and complexity of the requested analysis. Contact us for a personalized quote with no obligation.
What is a spectrogram and what is it used for?+
A spectrogram is a visual representation of the frequency spectrum of audio over time. It allows visual identification of anomalous patterns, cuts, insertions, acoustic environment changes, and other manipulations that are imperceptible to the human ear. It is a fundamental tool in audio forensic analysis.
Can the expert testify in court?+
Yes, our audio forensic experts are prepared to appear in court, ratify the expert report, play the analyzed recordings, explain the technical methodology applied, and answer questions from the court and parties. Their experience in acoustic forensics guarantees technical credibility.
What audio formats can you analyze?+
We analyze all common formats: WAV, MP3, M4A, AAC, FLAC, OGG, WMA, AMR, OPUS, and many others. We also work with proprietary formats from specific recorders, telephony systems, messaging applications, and video surveillance recordings. Uncompressed formats (WAV, FLAC) are ideal for forensic analysis.
Can you analyze a recorded phone call?+
Yes, we analyze phone call recordings regardless of origin: landline, mobile, VoIP, Skype, WhatsApp, recording applications, PBX systems, etc. We can determine if the recording is continuous, if it has been edited, and perform biometric analysis of the participating voices.
How long can the analyzed audio be?+
There is no technical duration limit. We analyze recordings from a few seconds to complete hours of audio (extended conversations, surveillance, interrogations, conferences). Analysis time and price are adjusted proportionally to the material length. For very long audio files, we can focus the analysis on specific segments of interest.
Can you recover a deleted WhatsApp audio?+
It depends on several factors: whether you have physical access to the device where it was deleted, the time elapsed, and whether new data has been written over that space. In some cases, we can perform forensic recovery of deleted data from the phone's internal storage. WhatsApp does not store deleted audio on its servers.
What technical information does the expert report include?+
The report includes: metadata analysis (date, time, recording device, software), complete frequency spectrogram, temporal waveform analysis, integrity verification through SHA-256 hashes, edit detection (cuts, insertions, speed changes), biometric voice analysis when applicable, acoustic environment evaluation, text transcription when relevant, precise timestamp identification of each finding, well-founded technical conclusions, and annexes with spectral graphs. All documented according to ISO/IEC 27037 computer forensics standards.
Is it legal to record a conversation I take part in?+
Yes. The Constitutional Court allows it (STC 114/1984): recording your own conversation does not violate the secrecy of communications. What constitutes a crime (art. 197 Criminal Code) is recording other people's conversations in which you do not take part.
How is a cut in an audio file detected?+
Background noise and the room's acoustic response leave a continuous signature: a splice interrupts it. The spectrogram will show discontinuities, anomalous silences or changes in encoding at the exact point of the edit.
Can you detect an AI-cloned voice?+
We analyze synthesis artifacts, the absence of natural micro-variations in breathing, and atypical spectral patterns. We indicate the degree of confidence; with high-quality clones the conclusion may be one of probability rather than certainty.
Can an audio file that is barely audible be improved?+
Often yes, through noise reduction and forensic equalization, both documented in the report. Any enhancement is performed on a copy and fully described, so that no one can allege manipulation on our part.
Does it include a transcript?+
It can be included, and it is usually very useful for the court. It is time-stamped and clearly distinguishes what is audible from what is uncertain.
Do documents signed online have the same validity as those signed in person?+
Exactly the same. Law 11/2023 recognises the full legal validity of notarial documents executed by video call with a qualified electronic signature before a registered notary.
Do I need a digital certificate?+
Yes, to sign electronically you need a digital certificate or an electronic DNI. If you do not have one, we help you obtain it quickly before your appointment, with no additional handling fee.
Can I do it from abroad?+
Yes, the notarial video call works from any country. You only need a stable connection, your valid identity document and a digital certificate.
How much does this service cost?+
The quote includes the official notarial fees set by the Notarial Association plus our handling, fixed before you start and with no hidden costs. Request it with no obligation via WhatsApp or the form.
What if I have questions during the process?+
Our team supports you from start to finish via WhatsApp, phone or email, and the notary answers all your legal questions before signing.
Ready to get started?
Request information with no obligation: we will contact you within 2 hours.
WhatsApp 930 485 101