Nowadays, any silent room with silent computer and microphone will do. Computer's fan, room noise, building noise and street noise are your main enemies. But most microphone hardwares are enough to record human voices fairly.
Recording using smartphone has proven surprisingly good, higher-end smartphones having dedicated sound-cards cleaning audio input from unwanted background noises.
This is a semi-professional recommendation :
- A silent room / recording studio
- A set comprising :
- A condenser microphone with a XLR output
- A headset to monitor your audio output
- An external sound card
- A XLR cable
- Possible accessories :
- A pod / arm stand
- An anti-pop filter
- An anti-vibration system
- A computer, even modest (the audio recording chain is external)
- A stable internet connection
Cost : ~ 250US$.