However, common house pets such as cats and dogs can also hear ultrasonic frequencies. Cats can perceive sound up to about 64,000 Hz, and dogs perceive sounds up to 45,000 Hz. You should consider not using noise as a repellent for mice if you have pets."

Humidifiers can also help ease symptoms of a cold or another respiratory condition. But be cautious and although useful, humidifiers can actually make you sick if they aren't maintained properly or if humidity levels stay too high. Dirty humidifiers can breed mold or bacteria.

Ultrasonic electronic pest and insect repellent devices claim that their high frequency sound waves are intolerable to rodents and insects. However, simply plugging in one of these devices probably won't end your pest woes. It's important to understand exactly what these devices can do before investing in one.