The electromagnetic manipulation should start from the emotional control, though there is a possibility that they should have created the disease at the early stage of their experiments. My point is that their capability has started from the simple manipulation to evoke several emotions, or to cause some brain damages including tumors and seizure which are fatal in many cases as those symptoms can be created by the simple frequency.
The voice can be sent to your brain directly through the electromagnetic wave, though it is not technically simple. You need to send a series of electromagnetic waves according to the voice sound frequencies, while the simple wave is just composed by the single frequency. The wave manipulation itself should not be problematic once the simple manipulation is established, though it cannot be a technology created at the onset.
The CIA originally targeted to read the thought inside the brain and their initial idea was utilization of microwave or infrared. I am more convinced they have used the electromagnetic wave around the microwave, which is characterized as straightness while still passing through the wall, which is not the case for the infrared.
This technology can read the ELF brainwave irradiated inside the brain, whose information can be taken out when we are exposed to the microwave. The outside electromagnetic wave can be transformed and reflected after interaction with the brainwave. That transformed wave can be decoded to recreate the brainwave.
The emotional control should be conducted by the extremely low frequency. The brain irradiates that frequency when the ionic change takes place inside the head, whose process can be controlled in the other way around. When our brain is exposed to the outside ELF, the corresponding chemical change should concur inside the brain. That is why our brain is manipulated by the outside electromagnetic irradiation.
The primary emotion can be controlled by simple frequencies, such as aggression. You become aggressive when exposed to the simple electromagnetic wave, which is also applicable to the stress, depression or anxiety.
On the other hand, the secondary emotion requires more complicated manipulation, such anger, love or anything. You become stressful and aggressive, but it is different from the anger which requires a subject to be angry with. The subject can be controlled by the electromagnetic manipulation, though they need to find out the reason and subject. You can target someone through the voice sent from the electromagnetic wave, but it is not composed of simple frequencies.