# PP+ Simple Harmonic Motion vs Stochastic Signal Processing

The clearest difference is review sentiment: Stochastic Signal Processing at 67% against PP+ Simple Harmonic Motion's 0%. Stochastic Signal Processing also leads on price (Free vs $1.99) and update cadence (every 5 weeks vs every 29 months). On ads and in-app purchases there is nothing between them.

Stochastic Signal Processing is free to download; PP+ Simple Harmonic Motion costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

PP+ Simple Harmonic Motion ships an update every 29 months, Stochastic Signal Processing every 5 weeks. The most recent releases landed on June 8, 2026 and September 25, 2026 respectively.

## The numbers

| Metric | PP+ Simple Harmonic Motion | Stochastic Signal Processing |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Rating | — | **[4.7 (6 ratings)](https://appshunter.io/ios/app/stochastic-signal-processing/id1450268179/reviews)** |
| Number of ratings | — | **6** |
| Positive reviews | 0.0% of reviews | **66.7% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 29 months | **Every 5 weeks** |
| Monetization | Paid | **Free** |
| Size | 115 MB | 73 MB |
| Requires iOS | 18.0 | **15.0** |
| Devices | iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Polyhedron Learning Media, Inc.](https://appshunter.io/developer/458882328) | [Ian Young](https://appshunter.io/developer/1450268178) |

## What reviewers say

### PP+ Simple Harmonic Motion

[App page](https://appshunter.io/ios/app/pp-plus-simple-harmonic-motion/id599165859)

Explore the principles of simple harmonic motion with a virtual spring-mass system. This educational tool provides realistic 3D simulations, data analysis tools, and comprehensive learning materials for students.

**Highlights:** 3D spring-mass simulation, Realistic data with errors, Data analysis and reporting tools, Introductory videos and background theory, Pre-lab quiz and post-lab questions, Teacher support materials

**Features:** macOS Compatibility

**In-app purchases:** none


### Stochastic Signal Processing

[App page](https://appshunter.io/ios/app/stochastic-signal-processing/id1450268179)

Explore the processing of random signals like speech, music, and climate data. This interactive textbook offers dynamic information, films, animations, and 59 real-time laboratory experiments using your device's camera and microphone. It's designed for those with prior signal processing and probability theory knowledge.

**Highlights:** Interactive textbook format, Dynamic information display, Films and animations, 59 laboratory experiments, Real-time signal processing, Homework problems

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is PP+ Simple Harmonic Motion free?

PP+ Simple Harmonic Motion costs $1.99, with no in-app purchases.

### Is Stochastic Signal Processing free?

Stochastic Signal Processing is free to download, with no in-app purchases.

### Do PP+ Simple Harmonic Motion or Stochastic Signal Processing have ads?

Neither PP+ Simple Harmonic Motion nor Stochastic Signal Processing shows ads.

### Which is updated more often, PP+ Simple Harmonic Motion or Stochastic Signal Processing?

PP+ Simple Harmonic Motion ships an update every 29 months, and Stochastic Signal Processing every 5 weeks. Most recently, PP+ Simple Harmonic Motion was updated on June 8, 2026 and Stochastic Signal Processing on September 25, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*