Brainwave entrainment is a simple concept. It’s simply causing your brainwave frequency to align with some intended frequency in order to produce some intended result. It’s a way of modulating your brainwaves to resonate at a certain frequency. Being that there are certain dominant frequencies associated with different states of consciousness, this is being researched as a quick and effective way to induce states such as sleep, alertness, concentration, and even meditative and deep sleep states.

They are not beyond what is “normal” but for most of us they are outside of what is “typical”. Whether we consciously seek them or not, somewhere in the back of our minds we hold beliefs that because meditation and brainwave entrainment are beyond our usual set of experiences, then the evidence that they are having some sort of effect on us must also be outside of our normal range of experiences.
However, those with ASD are sometimes also diagnosed with ADHD. Although they are different conditions, some of the symptoms can be intertwined, which it appears may be the case with your grandson. So I would start by trying out my tracks for ADHD. You can try those out for free on my YouTube channel and I’ve put them together in a playlist here: The corresponding MP3 versions for those tracks can be found on my site here: I hope that helps.
Theta brainwaves in the frequency range of 6 to 9 hertz are known as thalpha waves because of their proximity to alpha waves. They are seen during states of high suggestibility, during hypnosis, and during paranormal experience and are also connected to an increase in human growth hormone (HGH) levels and higher blood flow to the brain. Theta brainwaves sit between the realms of the subconscious and conscious mind, making them an especially useful brainwave state for developing creative thinking, working through emotional problems, and integrating subconscious and conscious experience. 
Entrainment guides our brainwaves into targeted ranges, but they are ranges we go through naturally many times every day. LifeFlow 10, for example, takes the brain to a 10Hz frequency. We experience this same frequency when closing our eyes and taking a deep breath, or when consciously relaxing physical tension in the body, or when we find ourselves lost in a daydream, or when we view a beautiful sunset, or when we find ourselves caught up in an especially peaceful bit of music. If there was a cause-and-effect relationship between these 10Hz brainwaves and our face flushing, then our face should also flush when we enter that daydream, listen to that piece of music, watch that sunset, or close our eyes and relax. The same brainwave patterns are present during all those activities as they are while listening to LF-10. But these other activities don’t bring on the same face flushing.
“The great neuroscientist W. Gray Walter carried out a series of experiments in the late forties and fifties in which he used an electronic stroboscopic device in combination with EEG equipment to send rhythmic light flashes into the eyes of the subjects at frequencies ranging from ten to twenty five flashes per second. He was startled to find that the flickering seemed to alter the brain-wave activity of the whole cortex instead of just the areas associated with vision. Wrote Walter, “The rhythmic series of flashes appear to be breaking down some of the physiologic barriers between different regions of the brain. This means the stimulus of flicker received by the visual projection area of the cortex was breaking bounds— its ripples were overflowing into other areas.”
While the physiological and psychological processes being uncovered by brain science in the study of brainwaves is sometimes complex and still being investigated, certain basic principles are well-established, easily understood, and helpful for achieving the most effectively use of brainwave entrainment when seeking relaxation, improved sleep, lowering of anxiety, or other goals. This important background information and scientific knowledge presented here includes: 
When signals of two different frequencies are presented, one to each ear, the brain detects phase differences between these signals. "Under natural circumstances a detected phase difference would provide directional information. The brain processes this anomalous information differently when these phase differences are heard with stereo headphones or speakers. A perceptual integration of the two signals takes place, producing the sensation of a third "beat" frequency. The difference between the signals waxes and wanes as the two different input frequencies mesh in and out of phase. As a result of these constantly increasing and decreasing differences, an amplitude-modulated standing wave -the binaural beat- is heard. The binaural beat is perceived as a fluctuating rhythm at the frequency of the difference between the two auditory inputs. Evidence suggests that the binaural beats are generated in the brainstem's superior olivary nucleus, the first site of contra-lateral integration in the auditory system (Oster, 1973). Studies also suggest that the frequency-following response originates from the inferior colliculus (Smith, Marsh, & Brown, 1975)" (Owens & Atwater, 1995). This activity is conducted to the cortex where it can be recorded by scalp electrodes.  
Binaural meditation music is VERY popular these days, and you might have noticed that some of the companies that sell binaural music products make rather spectacular claims about the benefits of brainwave entrainment technology. Some declare that they can make you “meditate like a zen monk at the touch of a button”, or that you will “instantly meditate like the greatest gurus”. While it is true that binaural meditation music is extremely powerful, and that it can genuinely improve the quality of your life, it is not a miracle solution or a spiritual “get rich quick” scheme. Like all things in life, positive and lasting results will still take just a little time and effort on your part. Binaural meditation music just accelerates and deepens to process.
Go behind the scenes of brainwave entrainment technology creation with Joseph Kao, developer of the extraordinary meditation tool Journey to the Center of the Self. Here, in an interview with John Dupuy, CEO of iAwake Technologies, Joe describes the amazing complexity of the brainwave entraining soundscape he created to both accompany his deeply inductive, 30-minute, guided meditation on the first track of Journey, and also stand alone as a music-only track that holds you in a profoundly relaxed, still, yet clear place on the theta/delta border. To find out all that went into the making of the inductive guided meditation on the first track of Journey, see A Guide to Transpersonal Meditation: Journey to the Center of the Self, part I of this interview.

When two pure tones of slightly different frequencies are delivered simultaneously to the two ears, is generated a beat whose frequency corresponds to the frequency difference between them. That beat is known as acoustic beat. If these two tones are presented one to each ear, they still produce the sensation of the same beat, although no physical combination of the tones occurs outside the... [Show full abstract]
Whenever we become very relaxed and the usual chatter of the mind slows down a little bit, if we remain aware and do not slip into sleep or unconsciousness, we begin to perceive things that we had not noticed before. This is slightly different than the issue of “expectations” discussed previously, although a relationship to them can develop which will be discussed below. These have to do with the fact that in our typical state of consciousness our mind is racing so fast and so loud, and our body is so engaged with activity and physical tension, that we are unaware of some subtle perceptions that are there all the while, but which get buried beneath all the physical and mental noise.
The final suggestion I have to offer is that you make your practice a regular, consistent habit. You don’t have to be perfect but you do need consistency. Like any other skill, entering meditation will develop in direct proportion to the consistency of your practice. Missing a session occasionally is not going to derail all your progress. But frequently skipping or blowing insincerely through practice is not going to produce any noteworthy results. There isn’t any hard and fast rule from frequency of practice that always applies to everyone, but most of us will instinctively know whether or not we’re giving our practice the time and effort it requires.
Binaural Beats or “binaural tones” are created by playing slightly different frequencies separately into each ear. The difference between the two frequencies stimulates a response in the brain which correlates with this frequency difference. For example, if we present a 100 Hz tone to the left ear and a 105 Hz tone to the right ear, a frequency of 5 Hz is stimulated. This is what is known as the “frequency following response”.
Eric Bartel is the creator of the Free Binaural Beats website and the sole creator of the audios found here. He specializes in creating binaural beats and isochronic tones along with relaxing ambient meditation music. From his home studio in the Black Hills of South Dakota, Eric is committed to bringing the healing power of binaural beats to anyone who wants to live a more peaceful, relaxed and fulfilled life.
This app offers an easy to use interface that helps you achieve certain states of mind for different activities. From headache treatment to IQ boost to Sleep Induction and Relaxation, this app offers frequencies for over 25 scenarios. If you’re looking for an app that will let you choose a state of mind or activity and then just hit play, this app would be great to use.
You don't have to buy one, though. It's not too hard to make your own binaural beat, and free software is widely available to do just that. The one that I used to make that little sample is an open-source program called Gnaural, available on the Sourceforge website. It's pretty easy to use, though it takes some practice before you can generate some of the really cool, more professional sounding beats. A binaural beat consists of two simple tones, and most people add that background pink noise. Nothing special.
“The great neuroscientist W. Gray Walter carried out a series of experiments in the late forties and fifties in which he used an electronic stroboscopic device in combination with EEG equipment to send rhythmic light flashes into the eyes of the subjects at frequencies ranging from ten to twenty five flashes per second. He was startled to find that the flickering seemed to alter the brain-wave activity of the whole cortex instead of just the areas associated with vision. Wrote Walter, “The rhythmic series of flashes appear to be breaking down some of the physiologic barriers between different regions of the brain. This means the stimulus of flicker received by the visual projection area of the cortex was breaking bounds— its ripples were overflowing into other areas.”
Nothing is more stressful than being unprepared. Get organized so you're ready for the next day, taking a few minutes to make a to-do list and clean up before you leave. Knowing you've got everything covered means you'll be less likely to fret about work in the evenings. When you come in the next morning, you'll have the sense that you're in control of the situation and can handle it. This sets a positive tone for the day, which can help you get more accomplished. (You can even turn your nightly beauty routine into a stress-relieving practice.)

Science shows that massages reduce stress, but you don’t have to go to the spa—you can give yourself one right now. “Learning how to self-massage your foot, head, neck, or shoulders reduces the stress hormone cortisol, boosts your immune system, and increases the feel-good hormones oxytocin, dopamine, and serotonin,” Dr. Serani says. You can even use a tennis ball or cold water bottle on your feet or neck. In addition, try rubbing pressure points like the webbing between your thumb and index finger, or your inner wrist. Another technique is the EFT tapping technique, literally tapping certain points on your body such as in between your eyes, your temples, and the center of your collarbone. “Tapping brings cleansing energy to the meridian points, as your mind directs the energy to what’s unbalanced in the body,” Whitaker says. “This restores your mind and body’s natural balance, which aids in releasing stress, worry, fears, and disharmony.”
Most programs start at a work/life busy brain Beta frequency of twenty light flashes per second (20Hz) and slowly ramp them down to Alpha (relaxation and meditation) at 8-12 HZ, Theta (deep relaxation and dreaming) at 4-8 Hz) and Delta (dreamless deep relaxation) of .5-4Hz. We have taken measurements at Mass General with state of the art EEG equipment and have seen a slowing of the brain waves from Beta to Theta in two minutes and complete brain wave harmonization in the left, right, anterior, posterior and occipital regions of the brain.
Uses of audio with embedded binaural beats that are mixed with music or various pink or background sound are diverse. They range from relaxation, meditation, stress reduction, pain management, improved sleep quality, decrease in sleep requirements, super learning, enhanced creativity and intuition, remote viewing, telepathy, and out-of-body experience and lucid dreaming. Audio embedded with binaural beats is often combined with various meditation techniques, as well as positive affirmations and visualization.

Because the brain filters and interprets reality in a split-brained way, we tend to see things as separate and opposed, rather than as connected and part of the oneness spoken of by the great spiritual teachers (and, in the last few decades, by quantum mechanical physicists). Thus, at a deep level, the dual structure of our brain, in conjunction with brain lateralization, predisposes us to see and experience ourselves as separate from, and often in opposition to, the rest of the world—instead of experiencing the elegant interconnectedness between us and everything else. Our childhood associations and programming build on this inborn tendency by training us to seek this and avoid that, to move toward pleasure and away from pain, to do good and not bad, and so on. The greater the lateralization in the brain, the greater the feelings of separation—and the greater the feelings of separation, the greater the fear, stress, anxiety, and isolation.
This is probably the most popular choice of frequency. The theta state is a state of tremendous stress relief. The benefits associated with theta level relaxation include improved concentration, reduced hyperactivity and improved memory. While in a state of theta relaxation, one’s blood pressure, breathing and heart rate all slow to a much more restful and healthy level that promotes natural healing. During theta relaxation one may also experience vivid flashes of mental imagery as the mind opens to memories or subconscious information that is not available to the conscious mind during the normal waking state. The theta state is a very deep state of relaxation that is excellent for deep hypnosis and mental programming.
^ Trost W. and Vuilleumier P., Rhythmic entrainment as a mechanism for emotion induction by music: a neurophysiological perspective. In The Emotional Power of Music: Multidisciplinary Perspectives on Musical Arousal, Expression, and Social Control, Cochrane T., Fantini B., and Scherer K. R., (Eds.), Oxford, UK: Oxford University Press; 2013, pp213–225.