Comparison

Convert to PDF vs Wavelet Voice Sonogram

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Convert to PDF

Transform various document and image files into PDF format quickly and easily. Upload files to the cloud for fast conversion, then share your new PDFs through multiple options. Supports over 2000 source formats.

Highlights
  • Convert over 2000 source formats to PDF
  • Save as document or ebook
  • Use 'Open with' for file loading
  • Load images from gallery or camera
  • Multiple sharing options
Features
Read full description

Convert to PDF allows you to convert almost all known document formats to PDF as an e-book or document. Convert existing documents, images or other file formats to PDF! And after the conversion you can use multiple ways of sharing the file! How can we convert almost every file on your phone? Well, the converting is accomplished by uploading your file to the cloud where it will be converted and downloaded back to your phone. This all occurs really fast. Features: - Over 2000 source formats are supported - Convert to PDF (.pdf) as a document or ebook - Use the 'Open with' option to load files - Use the image gallery to load an image or take one using the camera

About

Wavelet Voice Sonogram

Read full description

"Wavelet Voice Sonogram" is a sound spectrogram app that performs time-frequency analysis of acoustic signals. A spectrogram is a graph displaying the results of a sound frequency spectrum analysis, with time on the horizontal axis, frequency on the vertical axis, and signal strength represented by colors. This app can perform acoustic analysis and display the spectrograms by using three time-frequency analysis methods, Wavelet analysis, Octave Band analysis, and FFT analysis. It can also record sounds from iPhone's built-in microphone. While playing back a recording, you can search for the desired sound and analyze it. "Wavelet Voice Sonogram" makes it easy to analyze the acoustics of speech, instrumental sounds, noise, and more. It can also be used to learn the basics of speech analysis. Features: - Acoustic analysis can be performed using PCM data recorded with the iPhone's built-in microphone. It is possible to analyze 5 seconds of sound data backward from a user-specified point in time. - Three types of acoustic analysis, FFT analysis, octave band analysis and wavelet analysis, can be performed simultaneously. - PCM sound recording and playback is possible up to about 180 seconds, and the audio waveform graph and FFT analysis graph are displayed. While playing back sound, you can search for sound at any point in time. - Zoom in on a specific 10 seconds of PCM data and play back the sound. Used to find a specific sound at the point in time you want to analyze. - The spectrogram analysis result and time axis waveform can be contrasted and played back. Specifications: - Sampling frequency: 48 kHz - PCM recording time: approx. 180 seconds max. - Sound zoom function (10-Sec): Zooms in on any 10 seconds of PCM data and plays back the sound. - 3 types of acoustic analysis function (Analysis): About 5 seconds (Analysis points can be specified using the Time position slider.) -- FFT analysis (FFT): FFT 2048 points -- Octave band analysis (OCT): 1/48 octave band -- Wavelet analysis (DWT): Gabor Wavelet - Sound recording and playback, sound waveform and FFT graph display (Main): PCM graph, 10sec zoom graph, FFT graph. - Time position slider: Points to the cursor position on PCM graph. - Spectrogram display (FFT / OCT / DWT): 5 sec PCM graph and spectrogram analysis graph (vertical axis - time [0 - 5.0 sec], horizontal axis - frequency [100Hz - 8kHz]) - Snapshot (Snap): Save the analysis image in "Photos". Notes: - The acoustic analysis time varies significantly depending on the performance of your iPhone (product generation). It may take about 5 to 20 seconds. - Wireless (Bluetooth) headphones and headsets are not supported. - The first time the app accesses the built-in microphone and Photos after installation, the iOS system will ask you for permission to access them. If you have not enabled this setting, the application will not be able to access them due to iOS system privacy restrictions. Please enable the access permission in the iOS setting "Settings > Privacy & Security > Photos or Microphone". Please visit our iOS app support page for more information on this app.

Screenshots

Convert to PDF4 screens
Wavelet Voice Sonogram4 screens

Verdict

The call

The clearest difference is ads: Wavelet Voice Sonogram at none against Convert to PDF's shown. Wavelet Voice Sonogram also leads on update cadence (every 8 months vs every 20 months). Convert to PDF's advantage is price ($1.99 vs $6.99) and device support (3 vs 1). On in-app purchases there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Convert to PDF costs $1.99 and Wavelet Voice Sonogram $6.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Convert to PDF ships an update every 20 months, Wavelet Voice Sonogram every 8 months. The most recent releases landed on November 1, 2026 and October 25, 2026 respectively.

Scorecard5 real differences · 5 level
Convert to PDF versus Wavelet Voice Sonogram: the parameters behind the verdict, then further details
ParameterConvert to PDFWavelet Voice Sonogram
Price$1.99 — better$6.99
Rating5.0 (1 ratings) — better—
Positive reviews50.0% of reviews—
Number of ratings1 — better—
Update frequencyEvery 20 monthsEvery 8 months — better
AdsYesNo — better
In-app purchasesNoNo
MonetizationAd-supported—
DevicesiPhone, iPad, iPod — betteriPhone
Requires iOS11.0 — better26.2
Further details — not scored
Size81 MB0 MB
Age rating4+4+
DeveloperIce Cold AppsTOON,LLC

In-app purchases

None

Convert to PDF

No in-app purchases

None

Wavelet Voice Sonogram

No in-app purchases

Questions

Is Convert to PDF free?
Convert to PDF costs $1.99, with no in-app purchases.
Is Wavelet Voice Sonogram free?
Wavelet Voice Sonogram costs $6.99, with no in-app purchases.
Do Convert to PDF or Wavelet Voice Sonogram have ads?
Convert to PDF shows ads; Wavelet Voice Sonogram does not.
Which is updated more often, Convert to PDF or Wavelet Voice Sonogram?
Convert to PDF ships an update every 20 months, and Wavelet Voice Sonogram every 8 months. Most recently, Convert to PDF was updated on November 1, 2026 and Wavelet Voice Sonogram on October 25, 2026.

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