(Sound design notes:  The following describes a process to create a "ooooooooooooooooh" riser.  Actual implementation depends on the specific features of the "Riser Sound Effect Generator" which are not defined.  This response assumes a tool with capabilities for manipulating frequency, amplitude, and duration of sounds.)


**Phase 1:  Generating the Core Sound**

1. **Source Sound Selection:** Begin by selecting a source sound that has a naturally resonant and sustained quality.  A good starting point might be a low-pitched, sustained vowel sound ("ooh" or "aah") recorded from a human voice, or a synthesized equivalent.  The goal is to find a sound that already possesses the basic timbre you're aiming for.  Experiment with different vowel sounds and their variations to find the closest match to your target "ooooooooooooooooh".

2. **Pitch and Timbre Adjustment:**  Adjust the pitch of the source sound to a low, resonant frequency. This will provide the foundation for the deep, sustained quality of the "ooooooooooooooooh".  Fine-tune the timbre (tone color) to achieve the desired richness and warmth.  Consider adding subtle harmonic content to enhance the fullness of the sound.

3. **Initial Amplitude Setting:** Set the initial amplitude (volume) of the sound to a low level. This will allow for a gradual increase in volume as the riser progresses.


**Phase 2: Creating the Riser Effect**

1. **Amplitude Modulation:** The core of the riser effect lies in the gradual increase in amplitude.  The "Riser Sound Effect Generator" should allow you to define an amplitude envelope – a curve that dictates how the volume changes over time.  Experiment with different envelope shapes (linear, exponential, logarithmic, etc.) to find the most natural-sounding rise.  A smooth, gradual increase is key to avoiding a jarring or unnatural sound.

2. **Frequency Modulation (Optional):** To add subtle movement and interest, consider applying slow frequency modulation (vibrato).  A very slight, slow vibrato can add a sense of depth and warmth to the riser without distracting from the overall "ooooooooooooooooh" quality.  Avoid excessive vibrato, as this could detract from the desired effect.

3. **Duration Control:** Adjust the overall duration of the riser to match the desired length.  A longer duration will create a more dramatic and sustained effect, while a shorter duration will be more concise and impactful.

4. **Reverb and Delay (Optional):**  Adding a touch of reverb and/or delay can enhance the spaciousness and depth of the riser.  Use these effects sparingly to avoid muddying the sound.  A subtle reverb can create a sense of atmosphere, while a short delay can add a touch of shimmer.


**Phase 3: Refinement and Export**

1. **Automation:**  If the "Riser Sound Effect Generator" allows for automation, use it to fine-tune the amplitude, frequency, and other parameters over time.  This allows for greater control and precision in shaping the riser's character.

2. **A/B Comparison:**  Continuously compare your progress against your target "ooooooooooooooooh" sound.  Make adjustments as needed to achieve the desired quality.

3. **Export:** Once you are satisfied with the sound, export the riser as a high-quality audio file (e.g., WAV or AIFF) for use in your project.


This detailed process should guide you in creating your desired "ooooooooooooooooh" riser, assuming the tool provides the necessary functionalities. Remember to experiment and iterate to achieve the best results.